Timeline of Orthodox Church and Roman Catholic relations

This timeline of Orthodox Christian and Roman Catholic relations chronicles major dates which concern the relationship between the two communions.

Apostolic and Ante-Nicene Era

• ca. 37-53 Episcopacy of Apostle Peter in Antioch.
• 64 Martyrdom of Peter in Rome.
• 67 Election of Linus, first bishop of Rome.
• 135 First recorded use of title Pope by a Roman bishop (Hyginus).
• 210 Hippolytus of Rome, bishop and martyr and last of the Greek-speaking fathers in Rome, writes Refutation of All Heresies (Philosophumena), and Apostolic Tradition.
• 255 Cyprian of Carthage rejects Pope Stephen I's ruling on the Donatist controversy.

Conciliar Era

• 325 Original Nicene Creed ratified at First Ecumenical Council.
• 330 Founding of Constantinople as New Rome, renaming the city of Byzantium.
• 357 Pope Liberius signs Semi-Arian creed (possibly under duress).
• 379 Emperor Gratian permits Roman pope authority over neighboring bishops.
• 381 Nicene Creed expanded at Second Ecumenical Council.
• 382 First use of papal title Pontifex Maximus, as Emperor Gratian relinquishes the former pagan imperial religious title and bestows it on Pope Damasus I of Rome.
• 395-405 Series of correspondences between Augustine of Hippo and Jerome, where Augustine maintains the validity of the Septuagint, while Jerome favours the Hebrew (Rabinnical) Bible which becomes the OT basis for the Latin Vulgate.
• 410 Rome sacked by Visigoth invaders.
• 417 Pope Zosimus waffles on Pelagianism.
• 447 Pope Leo I wrote to the bishops of Sicily, rebuking them for permitting baptism at Epiphany, as the Greeks did, and ordering them to observe the Roman custom of baptizing on Easter and Whitsunday.
• 451 Fourth Ecumenical Council notes that Rome's primacy is because it was "the imperial city"; Tome of Pope St. Leo I endorsed by Council after review.
• 455 Rome sacked by Vandals.
• 476 Fall of the Western Roman Empire as Romulus Augustulus, the last Western Roman emperor, is deposed by the German Odoacer, leaving the emperor in the Greek East as the sole imperial authority, and an unstable political environment in the West where the Church of Rome slowly developed a centralized structure, concentrating religious as well as secular authority in the office of the Pope, the Bishop of Rome.
• ca. 537 Pope Vigilius allegedly writes letter endorsing Monophysitism.
• 537-752 Byzantine Papacy.
• 589 Insertion of Filioque into Nicene Creed by local council in Toledo, Spain.
• ca. 590-604 Pope St. Gregory the Great rejects the title of "universal bishop" for any bishop.
• 663-668 The island of Sicily passed to the Greek rite during the six years when Constans II made Syracuse his residence and the capital of the Byzantine Empire.
• 680-681 Sixth Ecumenical Council anathematizes Pope Honorius as a Monothelite heretic.
• 692 The Pentarchy form of government of universal Christendom by five patriarchal sees received formal ecclesiastical sanction at the Council in Trullo, held in Constantinople, which ranked the five sees as Rome, Constantinople, Alexandria, Antioch, and Jerusalem.
• 710 Last papal visit to Constantinople until 1967.
• ca. 750 Forging of the Donation of Constantine, a false document claiming to be from St. Constantine granting universal secular power to the Pope and his successors.
• 732-33 Byzantine Emperor Leo the Isaurian transfers the territories of Southern Italy (Sicily and Calabria), Greece, and the Aegean away from the jurisdiction of the Pope to that of the Ecumenical Patriarch in response to Pope St. Gregory III of Rome's support of a revolt in Italy against iconoclasm, in effect throwing the Papacy out of the Empire.
• 752 Founding of Papal States (lasting until 1870).

Estrangement and Schism

• 792 Charlemagne accuses "Greeks" of deleting Filioque from original Creed.
• 800 Usurpation of Western Roman Empire by Charlemagne.
• 809 Pope Leo III forbids addition of Filioque to Creed and has original Creed in both Greek and Latin inscribed on silver tablets displayed in Rome.
• 869-870 Robber Council of 869-870 deposes St. Photius the Great.
• 870 Gradual collapse of the Moravian mission beginning with the death of Prince Rostislav of Moravia, who is captured and deposed by his nephew, Svátopulk, who favours more the Latin liturgy and Bavarian clergy represented by the Frankish Bp. Wiching of Nitra (consecrated in 880 as the first Bp. of Nitria);
• 874 The Great Moravian king Svátopulk subjugated the Vistulan tribe of Lesser Poland, resulting in the Christianization of Little Poland in the Orthodox Cyrillo-Methodian style, (as opposed to the Western Bohemian style), as early as the end of 9th century, before the conversion of Polish King Mieszko I in 966;
• 879-880 Council in Constantinople (endorsed by papacy) reinstates St. Photius and anathematizes any changes to Nicene Creed, including the Filioque.
• 962 Founding of Holy Roman Empire.
• 966 Mieszko I, the first historical ruler of Poland, accepts Baptism, after marrying the Christian princess Dobrawa in 965, who as a Czech, had strong Orthodox connections.
• 996 After the repose of Pope John XV (985-996), the Frankish King Otto III installs his cousin Bruno of Carinthia as Pope Gregory V (996–999), the first German (non-Roman) Pope, marking the point at which the Roman papacy is converted to a Frankish organization.
• 1009 Patr. Sergius II of Constantinople removes name of Pope Sergius IV from the diptychs of Constantinople, because the pope had written a letter to the patriarch including the Filioque.
• 1014 First use of Filioque by Pope of Rome, at coronation of Holy Roman Emperor Henry II.
• 1022 At a Council of Pavia, Pope Benedict VIII officially reaffirmed the celibacy of the clergy (first documented at the Synod of Elvira in Spain, ca. 306 AD), banning marriages and concubines for priests.
• 1054 Excommunication of Ecumenical Patriarch Michael Cerularius by Cardinal Humbertus, papal legate, the conventional date point of the Great Schism. Michael returns the favor by excommunicating the Pope (who had died, rendering his legate's authority null).
• 1059 Beginning of the use of the term transubstantiation in West.
• 1066 Invasion of England by Duke William of Normandy, carrying papal banner and with papal blessing as a crusade against the "erring English church," engineered by Hildebrand, archdeacon of Rome.
• 1073-1085 Hildebrand becomes Pope Gregory VII and institutes Gregorian Reforms, the largest increase of papal power in history, including the claim to be able to depose secular rulers.
• 1075 Pope Gregory VII issues Dictatus papae, an extreme statement of papal power.
• ca. 1078-80 Council of Burgos reorganizes national Church of Spain as Roman Archbishopric, replaces use of Mozarabic rite with Roman. Sentences Bishops who refuse to recognize decrees to imprisonment.
• 1095-1272 Crusades promise salvation to warriors from the West.
• 1098 Abp. Anselm of Canterbury completes Cur Deus Homo, marking a radical divergence of Western theology of the atonement from that of the East; Pope Urban II called the Council of Bari, attended by more than 180 Roman Catholic bishops, including noted theologian Anselm of Canterbury (the founder of rationalistic Western Scholasticism) who defended the filioque clause, with the result that the Roman Catholic-dominated council affirmed the filoque and anathematized those who were opposed to it.
• 1139 Pope Innocent II declared all priestly marriages annulled and declared clerical celibacy the rule for all Roman Catholic priests from that day forward (Second Lateran Council, canons 6 and 7).
• 1170 Council of Constantinople, attended by many Eastern and Western Bishops, on the reunion of the Eastern and Latin Churches, without effect.
• 1180 Last formal reception of Latins to communion at an Orthodox altar, in Antioch.
• 1182 Maronites (formerly Monothelite heretics) submit to Rome.
• 1187 Saladin retakes Jerusalem after destroying crusader army at Battle of Hattin, and returns Christian holy places to the Orthodox Church.
• 1204 Fourth Crusade sacks Constantinople; Crusaders set up Latin Empire and Patriarchate of Constantinople (lasting until 1261).
• 1205 Latins annex Athens and convert the Parthenon into a Roman Catholic Church - Santa Maria di Athene, later Notre Dame d'Athene.
• 1211 Venetian crusaders conquer Byzantine Crete.
• 1224 The Byzantines recover Thessaloniki and surrounding area, liberated by the Greek ruler of Epirus Theodore Ducas Comnenus.
• 1231 Monk-martyrs and Confessors of the Monastery of Panagia of Kantara, on Cyprus, who suffered under the Latins (1231).
• 1234 Delegates of the two churches met first at Nicaea and then at Nymphaeum (Asia Minor), negotiating the issues related to the union of the Churches, including dogmatic issues, however the dialogue came to a dead end.
• 1236 Pope Gregory IX issued a crusading bull authorizing a crusade against the Byzantines under Emperor John Vatatzes, on the occasion of the joint Byzantine-Bulgarian siege of Latin Constantinople.
• 1259 Byzantines defeat Latin Principality of Achaea at the Battle of Pelagonia, marking the beginning of the Byzantine recovery of Greece.
• ca.1259-80 Martyrdom by Latins of monks of Iveron Monastery.
• 1260-1571 Subjugation of Church of Cyprus to the Roman Catholic Church.
• 1261 End of Latin occupation of Constantinople and restoration of Orthodox patriarchs; Emperor Michael VIII Palaiologos makes Mystras seat of the new Despotate of Morea, where a Byzantine renaissance occurred; Pope Urban IV endeavoured without success to stir up a crusade to restore the Latin Empire of Constantinople.
• 1263 Roman Catholic theologian Thomas Aquinas writes Contra Errores Graecorum (Against the Errors of the Greeks).
• 1264 The festival of Corpus Christi ("the Body of Christ") is instituted by Pope Urban IV.
• 1269 Orthodox patriarch returns to Antioch after a 171-year exile and usurpation by Latin patriarch.
• 1274 Council of Lyons fails to force Orthodox capitulation to papacy.
• 1281 Pope Martin IV authorizes a Crusade against the newly re-established Byzantine Empire in Constantinople, excommunicating Emperor Michael VIII Palaiologos and the Greeks and renouncing the union of 1274; French and Venetian expeditions set out toward Constantinople but are forced to turn back in the following year due to the Sicilian Vespers.
• 1282 Death of 26 martyrs of Zographou monastery on Mount Athos, martyred by the Latins.
• 1287 Last record of, Amalfion, Benedictine monastery on Mount Athos.
• 1300-1400 The "Chronicle of Morea" (Το χρονικό του Μορέως) narrates events of the establishment of Western European feudalism in mainland Greece, mainly in the Morea/Peloponnese, by the Franks following the Fourth Crusade, covering a period from 1204 to 1292.
• 1302 Papal bull Unam Sanctam declares submission to pope necessary for salvation.
• 1379 Beginning of Western "Great Schism," during which there are eventually 3 rival popes.
• 1341-1351 Councils in Constantinople vindicate Palamite theology of hesychasm against Barlaamist philosophy.
• 1409 Council of Pisa is convened and presided over by Cardinal de Malesset, Bishop of Palestrina, and attended by 4 Latin patriarchs, 22 cardinals, 80 bishops and hundreds of lower clergy, whereby both reigning Popes Gregory XII of Rome and Benedict XIII of Avignon were deposed as heretics, being a recognition of the fact that Patriarchs and Popes were subordinate to the Councils of the Church.
• 1414-1418 Council of Constance ends Western "Great Schism;" this council emphasized the Conciliar Movement over the authority of the pope.
• 1415 The 13th Session of the Council of Constance (June 15, 1415) decreed that the administering of the Eucharist in Both Kinds to the Laity was to be forbidden, and that the Laity should receive the Eucharist under one kind only, that of the Bread, even though the Council itself noted that: "Christ instituted and administered to his disciples this venerable sacrament under both kinds of bread and wine; and that it was received by the faithful in the primitive church under both kinds."
• 1423-24 Council of Siena in the Roman Catholic Church was the high point of conciliarism, emphasizing the leadership of the bishops gathered in council, but the conciliarism expressed there was later branded as a heresy.
• 1433 Nicolas of Cusa writes his major work on church government, The Catholic Concordance (De concordantia catholica), a manifesto of conciliarism, advancing the notion of a constitutional papacy subject to the authority of a council representative of the different parts of Christendom, balancing hierarchy with consent.
• 1439 Council of Florence fails to force Orthodox capitulation to papacy and confesses Purgatory as dogma; St. Mark of Ephesus courageously defended Orthodoxy at the Council of Florence, being the only Eastern bishop to refuse to sign the decrees of the council, regarded as a Pillar of Orthodoxy by the Church.
• 1444 Catholic priest Lorenzo Valla proves Donation of Constantine a forgery.
• 1450 Council of Constantinople convoked by Emperor Constantine XI Palaiologos declined to accept the resolutions passed by the Council of Florence which were in favor of the union of the Greek and Latin churches.
• 1452 Unification of Roman Catholic and Greek Orthodox Churches in the cathedral of Hagia Sophia on December 12, five months before the city fell. The union takes place on the West's terms, requiring the Orthodox to accept the Catholic position on all issues under dispute. Emperor Constantine XI Palaiologos, under pressure from Rome, allows the union to be proclaimed by the former Metropolitan of Kiev Isidore (who had participated in the Council of Florence and was now a cardinal in the Roman Catholic Church), who read the solemn promulgation of union and celebrated the union liturgy, including the name of the pope, arousing the greatest agitation among the population of the city.

Renaissance and Modern Era

• 1453 Fall of Constantinople to Ottoman Turks; numerous Greek scholars flee to West, triggering European Renaissance.
• 1463 Greek scholar and pro-unionist Basilios Bessarion, formerly an Orthodox Metropolitan, later becoming a Roman Catholic Cardinal, is given the purely ceremonial title of Latin Patriarch of Constantinople by Pope Pius II.
• 1472 Decrees of the Council of Ferrara-Florence repudiated by Patriarchate of Contantinople; martyrdom of Isidore of Yuriev and 72 companions for refusing to convert to Roman Catholicism.
• 1484 Synod of Constantinople with all four Patriarchs in attendance, calling itself "ecumenical", officially repudiated the union of the Greek and Latin churches discussed at Florence in 1439, and determined that Latin converts to Orthodoxy should be received into the Church by Chrismation.
• 1518 The Greek Orthodox Church of Saints Peter and Paul is founded in Naples, Italy, to serve the needs of Orthodox faithful who became refugees after the Fall of Constantinople.
• 1539 The Greek Orthodox Cathedral of Saint George in Venice is founded in Venice Italy (completed in 1573), to serve the needs of Orthodox faithful in the West.
• 1545-63 Council of Trent answers charges of Protestant Reformation.
• 1568 Pope Pius V recognizes four Great Doctors of the Eastern Church, John Chrysostom, Basil the Great, Gregory of Nazianzus, and Athanasius.
• 1569 Union of Lublin unites Kingdom of Poland and Grand Duchy of Lithuania into a single state, the Polish-Lithuanian Commonwealth, placing the Ruthenian Orthodox lands of Belarus, and modern Ukraine under direct Roman Catholic rule.
• 1573 Pope Gregory XIII establishes Congregation for the Greeks, a committee of cardinals who addressed issues relating to the Greeks in southern Italy and Sicily in the hope of resolving tensions between Greeks and Latins.
• 1576 Pope Gregory XIII establishes Pontifical Greek College of St. Athanasius (popularly known as the 'Greek College') in Rome, which he charged with educating Italo-Byzantine clerics.
• 1582 Institution of Gregorian Calendar.
• 1583 Arrival of the first Jesuits in Constantinople and constant proselytization by the Roman Catholic Church in the Ottoman Empire.
• 1595-1596 Pope Clement VIII declared in his Constitution Magnus Dominus (23 Dec. 1595), which announced the Union of Brest, that Orthodox Chrism was not valid and had to be repeated by a Roman Catholic bishop and that all Orthodox clergy had to accept the union; Union of Brest-Litovsk and creation of the Unia (Eastern/Byzantine/Greek Catholics); after initially having supported rapproachement with Rome, Bp. Hedeon (Balaban) of Lviv opposed the Union of Brest until his death; in Italy, the Greek language was forbidden in the liturgy and the College of St Athanasius (formally established in Rome in 1577) became one of the main centres of anti-Orthodox propaganda; Pope Clement VIII also replaced all Orthodox bishops with his own people, a policy that alienated local Orthodox populations, who yearned for the religious tolerance enjoyed by Ottoman subjects.
• 1597 Death of Nicephorus, the Protosyngellos of the Patriarch of Constantinople, who had supported the Orthodox synod at Brest (against the Uniate synod), and was sentenced to prison by the high court of Poland on charges of espionage.
• 1611 Gallican French theologian Edmund Richer (1559-1631), author of De ecclesiastica et politica potestate, held the view that ecclesiastical councils, not the papacy, was the method by which doctrinal truth was established, but his work was censured at the Council of Aix-en-Provence in 1612; this ‘richérisme’ strongly influenced 18th century Jansenism.
• 1620 Council of Moscow presided over by Patr. Philaret of Moscow insisted that only Orthodox Baptism by triple immersion was valid, and that all Latin converts had to be rebaptized.
• 1623 Death of turbulent Uniate Bp. Josaphat Kuntsevych who openly persecuted the Orthodox to such a degree that he was even rebuked by the Lithuanian chancellor Leo Sapiega, the representative of the Polish king himself.
• 1633 Ethiopian emperor Fasilides expels Jesuits and other Roman Catholic missionaries from Ethiopia.
• 1646 Union of Uzhhorod joins 63 Ruthenian Orthodox priests from the Carpathian Mountains to Roman Catholic Church on terms similar to Union of Brest.
• 1648 Martyrdom of Igumen Athanasius of Brest-Litovsk due to his very strong opposition to the Union of Brest.
• 1671 French Roman Catholic nun Margaret Mary Alacoque promoted devotion to the Cult of the Sacred Heart of Jesus in its modern form.
• 1672 Synod of Jerusalem convened by Patr. Dositheos Notaras, refuting article by article the Calvinistic confession of Cyril Lucaris, defining Orthodoxy relative to Roman Catholicism and Protestantism, and defining the Orthodox Biblical canon; acts of this council are later signed by all five patriarchates (including Russia).
• 1722 Council in Constantinople, in which Athanasios of Antioch (+1724) and Chrysanthos of Jerusalem (1707-1731) participated, decided for the re-baptism of the Latins.
• 1724 Melkite Schism, in which many Antiochian Orthodox become Greek Catholics; Old Catholic Schism: on October 15, 1724 Roman Catholic Bp. Dominique (Varlet) of Baghdad consecrated the first dissident bishop of Utrecht, Bp. Cornelius van Steenhoven (elected in 1723), as the Church of Holland, (or Church of Utrecht) broke with Rome under its own archbishop and hierarchy, becoming the mother church of the Old Catholic Churches.
• 1740 Pope Benedict XIV (Prospero Lorenzo Lambertini) promulgated the encyclical Pastoralis Romani Pontificis on March 30, in which he enforced and declared that he, his predecessors, and all his successors hold Papal Infallibility, and that ecumenical councils should be discouraged, as they can undermine one of the principle pillars of the papacy - infallibility.
• 1755 Synod of Constantinople declares Roman Catholic baptism invalid and ordered baptism of converts from Roman Catholicism.
• 1763 The Jansenist Provincial Council of Utrecht, seed of the future Old Catholic movements, affirmed every Roman Catholic dogma and pronounced the Orthodox Faith to be schismatic and false, signalling not so much a rapprochement with Orthodoxy, but rather a refusal to drift yet further from her, as much of the Roman fold was doing.
• 1767-1815 Suppression of the Jesuits in Roman Catholic countries, subsequently finding refuge in Orthodox nations, particularly in Russia.
• ca.1770 About 1,200 Kiev region Uniate churches return to Orthodoxy under political pressure from Russia.
• 1779 Death of New Hieromartyr and Equal-to-the-Apostles Kosmas Aitolos, who prophecied that Christians should condemn the position of the Pope since he will be the root of many catastrophes: ‘You should curse the Pope, because he will be the cause of harm.’
• 1793-95 Over 2,300 Uniate churches became Orthodox under Tsarina Catherine the Great.
• 1798 Patriarch Anthimus of Jerusalem contended in the Paternal Teaching (Dhidhaskalia Patriki) that the Ottoman Empire was part of the Divine Dispensation granted by God to protect Orthodoxy from the taint of Roman Catholicism and of Western secularism and irreligion.
• ca.1830 Slavophile movement co-founded by Alexei Khomiakov and Ivan Kireyevsky in Russia, drawing on the works of Greek patristics, Russian poets and literary critics to reinforce Orthodox Christian values and Slavic cultural traditions, denouncing "westernizations" by Peter the Great and Catherine the Great, and stressing Russian mysticism over Western rationalism.
• 1838 Council of Constantinople held, attended by Patriarchs Gregory VI of Constantinople and Athanasius V of Jerusalem, whose main theme was the Unia, and the extermination of Latin dogmas and usages, in particular Absolution Certificates.
• 1842 Russian diplomat Ivan Sergeyevich Gagarin converted to the Roman Catholic Church and joined the Jesuit Order, becoming dedicated to union between the Orthodox and Roman Catholic churches.
• 1847 Restoration of Latin Patriarchate of Jerusalem by Pope Pius IX; 1847 Agreement between the Holy See and Russia.
• 1848 Encyclical of the Eastern Patriarchs sent by the primates and synods of the four ancient patriarchates of the Orthodox Church, condemning the Filioque as heresy, declaring the Roman Catholic Church to be heretical, schismatic, and in apostasy, repudiating Ultramontanism and referring to the Photian Council of 879-880 as the "Eighth Ecumenical Council."
• 1853-56 Crimean War is fought between Russia on the one hand, and the Ottoman Empire, Britain, France, and (later) Sardinia on the other, ostensibly over which church would be recognized as the "sovereign authority" of the Christian faith in the Holy Land, and over Russia's claim of protection over the Greek Christians in the Turkish Empire; the French Catholic Abp. of Paris Marie-Dominique-Auguste Sibour pronounded that this was a holy war against the Orthodox.
• 1854 Declaration of Immaculate Conception of Mary as dogma.
• 1857-66 J.P. Migne produces the Patrologia Graeca in 161 volumes, including both the Eastern Fathers and those Western authors who wrote before Latin became predominant in the Western Church in the 3rd century.
• 1863 Abbé Vladimir Guettée, a French Roman Catholic priest who converted to the Orthodox Church, writes "The Papacy: Its Historic Origin and Primitve Relations with the Eastern Churches", a strong criticism of the Papacy.
• 1870 Declaration of Papal Infallibility to be dogma at First Vatican Council.
• 1875 Uniate diocese of Chelm in modern day Poland incorporated into Russian Orthodox Church under Alexander II, with all of the local Uniates converted to Orthodoxy.
• 1889 Roman Catholic priest Fr. Antonio Francisco Xavier Alvares (Julius of Goa) and hundreds of Goan Catholic families (approximately 5000 Roman Catholics) left the Roman Catholic Archdiocese of Goa and Daman and joined the Malankara Orthodox Syrian Church as the Independent Catholic Church of Ceylon, Goa and India, with Fr. Antonio being ordained as the first (Latin-Rite) Oriental-Orthodox Metropolitan of Goa-Ceylon (1889-1923).
• 1894 Praeclara Gratulationis Publicae (on the Reunion of Christendom), an Encyclical Letter of Pope Leo XIII promulgated on June 20, called for the reunion of Eastern and Western churches into the "Unity of the Faith", while also condemning Freemasonry; criticized by Ecumenical Patriarch Anthimus VII in 1895; Pope Leo XIII issues Orientalium Dignitas, a papal encyclical concerning the Eastern Catholic Churches including a prohibition aganist Latinizing influences among Eastern Catholics.
• 1895 Council of Constantinople, convened and presided over by Patriarch Anthimus VII, and attended by 13 bishops, condemns all the Franco-Latin heresies, including the new false dogma of the so-called Immaculate Conception of the Virgin Mary by St. Anne, and the blasphemous teaching that the pope is supposedly infallible and undeposable.
• 1908 English Roman Catholic priest and Byzantine scholar Dr. Adrian Fortescue writes The Orthodox Eastern Church, written to teach Roman Catholics and people in the West about the Orthodox Church.
• 1914 Martyrdom of Fr. Maxim Sandovich, Protomartyr of the Lemko people.
• 1918 The "St. Sophia Redemption Committee" is formed in Britain after the Armistice, whose members included two future Foreign Secretaries and many prominent public figures, seeking to restore Hagia Sophia into an Orthodox Church (1918-1922); Roman Catholic opposition to the St Sophia Redemption Committee included Msgr. Manuel Bidwell (Chancellor of the Archdiocese of Westminster) who was on the initial committee, Roman Catholic British MP Sir Stuart Coats also on the committee, Cardinal Pietro Gasparri the Papal Secretary of State, and the Vatican who wished to block Hagia Sophia from becoming a Greek Orthodox Church again according to the Grand Vizier of Constantinople who had an offer of Papal support.
• 1924-26 Cathedral of Alexander Nevsky (Warsaw) is demolished by Polish authorities less than 15 years after its construction.
• 1923 Pope Pius XI proclaimed the controversial Uniate Bp. Josaphat Kuntsevych a "hieromartyr" on the 300th anniversary of his death, in the encyclical Ecclesiam Dei (The Church of God).
• 1925 Concordat of 1925 between Poland and the Holy See included recognition of the Uniate Church in Poland.
• 1926 The Benedictine monastery Chevetogne Abbey is founded in Belgium, dedicated to Christian unity, being a ‘double rite’ monastery having both Western (Latin rite) and Eastern (Byzantine rite) churches holding services every day; the Society of St. John Chrysostom is founded to promote awareness and friendship in the Christian West for Christians of the East, through prayer and liturgy, conferences and lectures, and praying for the unity of the Churches of East and West; Pope Pius XI decides to attempt the establishment of a provisional hierarchy for the Roman Catholic Church without the knowledge of the Soviet government; French Jesuit scholar and Roman Catholic bishop Michel d'Herbigny receives episcopal ordination in secret and behind closed doors from Eugenio Pacelli (the future Pope Pius XII) in the failed attempt to establish a clandestine hierarchy for the Catholic Church in the Soviet Union during the religious persecutions of the 1920s.
• 1929 Papacy and the Kingdom of Italy ratify the Lateran Treaty, recognizing sovereignty of Papacy within the new state of the Vatican City, bringing to an end the so-called "Roman Question"; Russicum (Russian College or 'College of St. Therese') founded in Vatican City by Pope Pius XI and run by the Jesuits; Papal Bull Cum data fuerit regulates Uniate clergy in the US, mandating celibacy, resulting in the return of several parishes back to Orthodoxy in 1938.
• 1930 A Pan-Orthodox Consultation in Mount Athos concluded that the only possible relations on the part of the Orthodox toward the Roman Catholics was "Relations of defense on the part of the Orthodox toward Roman Catholic Proselytism."
• 1937 Pope Pius XI issued the encyclical Divini Redemptoris, condemning Communism and the Soviet regime; the Serbian Orthodox Church led by Patr. Varnava (Rosic) of Serbia and Bp. Nikolai Velimirovic fiercely resisted the attempt by the government of Yugoslavian Prime Minister Milan Stojadinović to implement a Concordat with the Vatican, which would have virtually established the Roman Catholic Church in Yugoslavia and granted it privileges denied to the Orthodox Church, resulting in the proposal never being ratified.
• 1938 In the Volhynia region of modern day Western Ukraine, by 1938 the Polish government had overseen the destruction of 190 Orthodox churches and converted a further 150 churches to Roman Rite Catholicism, despite its Ukrainian majority, and despite Pope Leo XIII's encycical Orientalium Dignitas of 1894; the few Orthodox churches that were permitted to stay open were forced to use the Polish language in their liturgies. American Carpatho-Russian Orthodox Diocese founded, when a group of 37 Carpatho-Russian Eastern Catholic parishes, under the leadership of Fr. Orestes Chornock, were received into the jurisdiction of the Ecumenical Patriarchate.

WWII and Post-WWII Era

• 1939 The last remaining Orthodox Church in Lutsk, the Volhynian capital was converted by Polish State decree to Roman Rite Catholicism.
• 1941-45 Croatian Ustasa terrorists, part of whose ideology included Roman Catholic Clericalist Fundamentalism, kill 500,000 Orthodox Serbs, expel 250,000 and force 250,000 to convert to Catholicism; the Orthodox in Croatia were forced to wear the Cyrillic letter "P" for Provoslavets, or Orthodox, like the Jews who were forced to wear the Star of David during World War II; martyrdom of Bp. Sava of Gornji Karlovac, and Fr. Djordje Bogic.
• 1943-44 Hundreds of Orthodox priests of the Ukrainian Orthodox Church eliminated, tortured and drowned by Organization of Ukrainian Nationalists - Ukrainian Rebel Army, aided by Uniate Metr. Josyf Slipyj who was a spiritual leader of Nazi military units that were later condemned by the Nuremberg tribunal, and who was imprisoned by Soviet authorities for aiding the UPA; zenith of the Papist persecution in Poland against Orthodox faithful in the region of Helm and Podlaskia - Holy Poles martyred by the Papists.
• 1946 Metr. John of Kiev received Fr. Gabriel Kostelnik and twelve other priests from the Unia to Orthodoxy; state-sponsored synod held in Lviv Ukraine dissolves the Union of Brest-Litovsk and integrates the Ukrainian Greek Catholic Church into the Russian Orthodox Church, with Soviet authorities arresting resisters or deporting them to Siberia; Croatian Roman Catholic Abp. of Zagreb Aloysius Stepinac is tried and found guilty of collaboration with the fascist Ustaše movement and complicity in allowing the forced conversions of Orthodox Serbs to Catholicism;
• 1947 Death of Alexei Kabalyiuk, Apostle of Carpatho-Russia, who played a major role in reviving Orthodoxy in Transcarpathia in the early 20th century.
• 1948 Martyrdom of Carpatho-Russian priest Protopresbyter Gabriel Kostelnik.
• 1949 Papal Decree against Communism by Pope Pius XII excommunicates all Catholics collaborating in communist organizations.
• 1950 Declaration of Bodily Assumption of Mary as dogma.
• 1952 Ecumenical Patr. Athenagoras officially visited, for the first time in the last one thousand years, the Papal representative in Constantinople, who returned the visit.
• 1958 Pope John XXIII and Ecumenical Patr. Athenagoras exchanged formal letters calling for peace among the Christian churches.
• 1962 The secretive Metz Accord is made between the Holy See and the U.S.S.R. (attended by Metr. Nikodim (Rotov) of Leningrad) at Metz, France, on 13 August 1962, renewing the previous pacts of 1942 and 1944 concerning the Vatican's Ostpolitik, by which Eastern Orthodox participation in the Second Vatican Council was authorized in exchange for a non-condemnation of atheistic communism during the conciliar assemblies.
• 1962-1965 Vatican II institutes major reforms, especially liturgical, into Roman Catholic Church; Patr. Maximos IV Sayegh of the Melkite Greek Catholic Church urged reconciliation between the Catholic and Eastern Orthodox churches, spoke forcefully against the Latinization of the Eastern Catholic Churches, and championed the Eastern tradition of Christianity, winning a great deal of respect from Eastern Orthodox observers at the council and the approbation of the Ec. Patr. Athenagoras I.
• 1963 Pope Paul VI announced the relaxation of the Roman Catholic ban on cremation in a confidential letter to bishops and issued his Instruction on 5 July, 1963.

Era of Dialogue

• 1964 Mutual lifting of excommunications by Patr. Athenagoras I and Pope Paul VI.
• 1965 The North American Orthodox-Catholic Theological Consultation is founded, meeting twice yearly; the office of Latin Patriarch of Constantinople is officially abolished; Professor John Karmiris wrote about the Vatican’s plan to promote the union of the Orthodox and Papist, stating: "Pope Paul VI and his circle of Papist theologians worked out a well-researched and broad program of Rome-centered Ecumenism, in agreement with Latin Ecclesiology."
• 1966 Translation of the sacred relics of the Holy Apostle Titus of Crete, from Venice (which took them in 1669), back to the Greek Orthodox Archdiocese of Crete.
• 1966-67 Pope Paul VI continued John XXIII's policy of dialogue with Soviet leaders in order to reduce persecutions against local Christians (Ostpolitik policy), receiving Foreign Minister Andrei Gromyko and USSR President Nikolai Podgorny; however while the Soviet officials considered themselves calling on the pope as the head of the Vatican City State, the Vatican announced the visit as made to the Holy Father as supreme pastor of the Holy See.
• 1968 The Pope removed from the Calendar of Saints the Great-Martyr St. George the Trophy-bearer, as well as erasing thirty other Saints with him, including Saint Nicholas, Saint Christopher, Saint Barbara, and Saint Catherine, being some of the chief Saints of Orthodoxy. visit to Patriarchate of Alexandria by Vatican representatives, who give Patr. Nicholas VI a part of the relics of St Mark from Venice, on behalf of Pope Paul VI; the Centro Pro Unione center is founded by the Society of the Atonement (Graymoor Friars and Sisters) as an ecumenical research and action center;
• 1969 The new Roman Missal Institutio Generalis Missalis Romani or General Instruction of the Roman Missal (GIRM) is issued, indicating a preference for the liturgical orientation in which the priest celebrates the Liturgy "Versus Populum" ("towards the people"), rather than "Ad Orientem" ("towards the east"), becoming the new pattern worldwide in Roman Catholic parishes.
• 1974 The Venerable Justin Popović wrote "The Orthodox Church and Ecumenism", noting that: "Ecumenism is a common name for the false Christianities of the false churches of Western Europe. Within it is found the heart of European Humanism with Papism as its head. All of these false Christianities and false churches are nothing other than one heresy next to the other. Their common evangelical name is pan-heresy."
• 1978 Through the efforts of Metr. Panteleimon (Chrysofakis) of Thessalonica, the sacred relics St. David of Thessalonica were triumphantly returned to Thessaloniki from Milan, Italy, after having been taken by Crusaders in 1236 AD.
• 1979 Joint Commission of Orthodox and Roman Catholic Churches for Theological Dialogue established.
• 1980 Extraordinary Joint Conference of the Sacred Community of Mount Athos, April 9-22, resolved publicly to state the opinion of the Athonite fathers on the subject of dialogue with the heterodox; Greece and the Vatican City State formally established diplomatic relations; Pope John Paul II called the first officially recognized synod of the Ukrainian Greek Catholic Church (UGCC), presided over by controversial wartime Metr. (now Cardinal) Josyf Slipyj.
• 1982 Orthodox-Roman Catholic Joint Commission publishes in Munich first official common document, "The Mystery of the Church and of the Eucharist in Light of the Mystery of the Holy Trinity."
• 1984 Martyrdom of Bp. Paul (de Ballester-Convallier) of Nazianzus in Mexico.
• 1985 Joseph Cardinal Ratzinger (later Pope Benedict XVI) issues The Ratzinger Report: An Exclusive Interview on the State of the Church, where he caricatures all Eastern Orthodox Churches as doctrinally "static" and "petrified as it were."
• 1987 Orthodox-Roman Catholic Joint Commission in Bari issues common document "Faith, Sacraments and the Unity of the Church."
• 1988 Orthodox-Roman Catholic Joint Commission in Valamo publishes common document "The Sacrament of Order in the Sacramental Structure of the Church;" Pope John Paul II addressed the European Parliament urging unity with the East.
• 1989 Joseph Cardinal Ratzinger (later Pope Benedict XVI) publishes "Letter to the Bishops of the Catholic Church on Some Aspects of Christian Meditation," where he rehearses historical heretical arguments against hesychasm (in sections 26-28), caricaturing hesychasm as a "psychological-corporal method" with numerous inherent dangers.
• 1990 The Soviet Union and Holy See established official relations 15 March 1990.
• 1993 Orthodox-Roman Catholic Joint Theological Commission meets in Balamand, Lebanon, issuing common document "Uniatism: Method of Union of the Past, and Present. Search for Full Communion" (the "Balamand document"); the Balamand Document declared that what has been called "uniatism" "can no longer be accepted either as a method to be followed nor as a model of the unity our Churches are seeking".
• 1995 Pope John Paul II issues Apostolic Letter Orientale Lumen ("Light from the East") on May 2, encouraging East-West union; Pope John Paul II issues Encyclical Ut Unum Sint ("That they may be one") on May 25, reiterating that unity of these two sui juris churches is essential (as well as further dialogue with the Protestant churches), showing that the Roman Catholic Church is officially moved to unity.
• 1997 Beginning of the annual series of Orientale Lumen Conferences, a grassroots movement among lay persons and clergy providing a common forum for Eastern Orthodox, Eastern Catholics and Roman Catholics to meet and learn about eachother's traditions; "Orientale Lumen I" is held in Washington D.C.
• 1998 Pope John Paul II beatified Zagreb's controversial wartime Abp. and later Cardinal Aloysius Stepinac.
• 2000 Orthodox-Roman Catholic Joint Theological Commission meets in Baltimore, but is suspended after an acrimonious meeting, in particular due to the issues of papal primacy and the role of Eastern Catholic Churches, with the Commission not resuming again for six years; in view of the celebration of the Roman Catholic Great Jubilee year (Jubilaeum), on Sunday March 12 in his "Day of Pardon" homily Pope John Paul II formally asked forgiveness for the various sins committed by the Roman Catholic Church over the last two millennia.
• 2001 Pope John Paul II apologizes to Orthodox for Fourth Crusade, on the first trip to Greece by a Pope since AD 710; a day earlier some 1,000 Orthodox conservatives took to the streets to denounce his visit; Pope John Paul II goes on a controversial visit to Ukraine during which he was fiercely opposed by that country's largest Orthodox Church, where he beatified 28 Greek Catholics, including 27 martyrs, most of whom were killed by the Soviet secret police.
• 2002 Patr. Bartholomew I (Archontonis) of Constantinople and Pope John Paul II co-sign Venice Declaration of Environmental Ethics; problem of Vatican proselytism is highlighted in its decision to upgrade its four Apostolic Administrations in Moscow, Saratov, Novosibirsk and Irkutsk to fully fledged Diocese status, and elevate the former Apostolic Administrator, Msgr. Tadeusz Kondrusiwicz, to Metr.-Abp. of Moscow, drawing a storm of protest from Patr. Alexei II and the Holy Synod of Russia who described the move as "unfriendly" claiming the Roman Catholic Church saw Russia as a field for missionary activity.
• 2003 Holy Synod of the Church of Poland canonizes the Holy Polish Saints and Martyrs of the eparchy of Helm and Podlaskia, martyred by the Papists during the zenith of the persecutions in 1944.
• 2004 Return of relics of Ss. John Chrysostom and Gregory the Theologian to Constantinople from Rome (after having been stolen by Crusaders); the Orientale Lumen EuroEast I conference is held in Istanbul, May 10-13, 2004; the Saint Irenaeus Joint Orthodox-Catholic Working Group is established at Paderborn (Germany), composed of 26 theologians, 13 Orthodox and 13 Roman Catholics, attempting to go through Church history chronologically to understand and analyze the development of the interrelationship between primacy and synodality in terms of both theology and praxis. In the same year, Patriarch Alexei II of Moscow expressed his discontent over the tensions caused by a series of unfriendly moves by the Vatican. He referred to the creation of four Catholic dioceses in Russia, two dioceses in Kazakhstan and two episcopal sees in the traditionally Orthodox regions of Ukraine. From the point of view of canon law, this meant the actual creation of parallel local churches.
• 2005 Major controversy in Ukraine involving the almost exclusively western Ukraine-based Uniate Greek Catholic Church moving its administrative centre on from Lviv to Kiev, constructing a large cathedral there, and its plans to establish a patriarchate, criticized by the Orthodox Church of Ukraine and other Orthodox; in his first major policy statement as pope, Pope Benedict XVI issued an instruction barring actively gay priests from seminaries, the only exception being for those with a "transitory problem" that had been overcome at least three years prior to ordination to the diaconate.
• 2006 Pope Benedict XVI drops title Patriarch of the West; Pope Benedict XVI visits Ecumenical Patriarchate, drawing criticism from the common Assembly of the twenty Sacred Monasteries of Mount Athos; in Ephesus, during the 2006 visit of Benedict XVI to Turkey and to the Phanar, he supported the Unia, stating "according to him the best way to unity in the Church is that of Unia." Abp. Christodoulos (Paraskevaides) of Athens visits Vatican, the first head of the Church of Greece to visit the Vatican, reciprocating the Pope's visit to Greece in 2001, and signing a Joint Declaration on the importance of the Christian roots of Europe and protecting fundamental human rights; the Russian Orthodox and Roman Catholic Churches confronted Secular Humanism at the conference "Giving a Soul to Europe" (Vienna, May 3-5, 2006), discussing the challenges facing Christianity, specifically materialism, consumerism, agnosticism, secularism and relativism, all based on liberal humanist ideology, constituting a real threat to Christianity today; Pope Benedict XVI met with Bp. Agathangelos of Fanarion and Greek Orthodox Seminarians from the Apostoliki Diakonia theology college in Greece who were visiting Rome, urging them to confront the challenges that threaten the faith by working to unify all Christians.
• 2007 Orthodox-Roman Catholic Joint Commission meets in Ravenna, Italy, 10th plenary, led by co-presidents Cardinal Walter Kasper and Metr. John (Zizioulas) of Pergamon, agreeing upon a joint document consisting of 46 articles providing an ecclesiastical road map in discussing union ("Ravenna Document"); Russian delegation walks out of Ravenna talks in protest of presence of Estonian delegation (EP); the Vatican issued a 16-page document prepared by the Congregation for the Doctrine of the Faith, restating its belief that the Catholic Church is the only true church of Jesus Christ, also stating that although Orthodox churches are true churches, they are defective because they do not recognize the primacy of the Pope; Orientale Lumen EuroEast II conference, May, 2007 in Istanbul; the Vatican formally reconsiders doctrine of Limbo; Pope Benedict XVI issues the Apostolic Letter Summorum Pontificum, granting greater freedom to use the Tridentine Mass in its 1962 form and for administering most of the sacraments in the form that they had before the liturgical reforms following the Second Vatican Council, being well received by supporters of the Tridentine Mass and Traditionalists.
• 2009 Led by three senior archbishops, a group of Orthodox clergy in Greece published a manifesto, A Confession of Faith Against Ecumenism, pledging to resist all ecumenical ties with Roman Catholics and Protestants, amongst its signatories including six metropolitans, as well as 49 archimandrites, 22 hieromonks, and 30 nuns and abbesses, as well as many other priests and church elders; Orthodox-Roman Catholic Joint Commission meets in Paphos, Cyprus, 11th plenary, studying the theme "The Role of the Bishop of Rome in the Communion of the Church in the First Millennium;" first-ever Russian Orthodox church is consecrated in Rome; Russia and the Holy See upgraded their diplomatic relations to full ambassadorial relations in 2009, following improvements in the working relationship between the Holy See and the Orthodox Patriarchate of Moscow; at the invitation of Cardinal Walter Kasper, Abp. Hilarion (Alfeyev) of Volokolamsk visited Pope Benedict XVI and several officials of the Roman Curia who have key roles in the Roman Catholic ecumenical dialogue; the North American Orthodox-Catholic Theological Consultation issues "A Common Response" to the Ravenna Document of 2007, identifying a number of criticisms.
• 2010 Patr. Bartholomew firmly addressed the opponents of the Orthodox theological dialogues in the Patriarchal and Synodal Encyclical on the Sunday of Orthodoxy, signed by 12 Bishops in addition to the Ecumenical Patriarch; first ever visit by a pope to Cyprus, as Pope Benedict went on a sensitive three-day day visit to the divided island; Cardinal Walter Kasper stated that there can be no full integration of eastern and western Europe without ecumenical dialogue and the contribution of the eastern European Orthodox churches; at the “Orthodox Constructions of the West” conference at Fordham University (June 28-30), keynote speaker Fr. Robert F. Taft, (S.J) delivered the address "Perceptions and Realities in Orthodox-Catholic Relations Today," calling on Catholic and Orthodox Churches to Restore Communion; Pope Benedict XVI proclaims the Pontifical Council for the Promotion of the New Evangelisation; Orientale Lumen EuroEast III conference, July 5-8, 2010 in Istanbul; Orthodox-Roman Catholic Joint Commission meets in Vienna, Austria, 12th plenary, studying the theme "The Role of the Bishop of Rome in the Communion of the Church in the First Millennium;" North American Orthodox-Catholic Theological Consultation meets in Washington DC, issuing two statements: Steps Towards A Reunited Church: A Sketch Of An Orthodox-Catholic Vision For The Future., and Celebrating Easter/Pascha Together. Croatian Roman Catholic Archdiocese of Zadar gives cherished relic of St. Simeon to the Greek Orthodox Patriarchate of Jerusalem; over half a million Guatemalan Indians of the "Orthodox Catholic Church of Guatemala" (OCCG), a branch of the "Orthodox-Catholic Church of America" (OCCA), are received in their entirety into the Ecumenical Patriarchate's Holy Metropolis of Mexico (Central America); renowned Swiss theologian and Patristics scholar Hieromonk Gabriel Bunge (O.S.B.) is received into the Orthodox Church.
• 2011 The United States Conference of Catholic Bishops (USCCB) releases a revised edition of the New American Bible which further departs from the authority of the Septuagint, in favour of the later Masoretic text, most controversially in Isaias 7:14, revising the NAB from "the virgin shall be with child" to "a young woman shall be with child", essentially serving to undermine the doctrines of the Perpetual Virginity of the Theotokos, and the Virginal Conception of Christ; official introduction of the new English-language translation of the Roman Missal in most English-speaking countries, on the first Sunday of Advent (November 27, 2011), representing a translation that more faithfully tracks the original Latin.
• 2012 The Assembly of Catholic Ordinaries of the Holy Land (ACOHL) issues a directive stating that within two years (by 2015) all Eastern Catholics and the Latin Patriarchate in the Holy Land will officially adopt the Greek Orthodox Julian calendar date for the celebration of Pascha.
• 2014 Metropolitans Seraphim of Piraeus and Andrew of Dryinoupolis, of the Church of Greece, write a lengthy epistle sent to to Pope Francis on April 10, 2014, concerning his past, the abysmal State of Papism, and a plea to return to Holy Orthodoxy.

See also

• Church of Rome
• Roman Catholic Church
• Heterodoxy
• Anti-Orthodox - Roman Catholic Polemics

• Great Schism
• Ecclesiology
• Primacy and Unity in Orthodox Ecclesiology

• Orthodox - Old Catholic Dialogue
• Timeline of Church History
• Timeline of Schisms

External Links

Wikipedia

• Roman Catholic–Eastern Orthodox theological differences
• Joint International Commission for Theological Dialogue Between the Catholic Church and the Orthodox Church
• North American Orthodox-Catholic Theological Consultation
• Pontifical Council for Promoting Christian Unity
• Pontifical Oriental Institute (The premier center for the study of Eastern Christianity in Rome, Italy).
• Catholic Church and ecumenism

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• Catholic–Orthodox Joint Declaration of 1965
• Declaration of Ravenna (2007)

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• Roman Catholic Church
• Latin Church
• Latin liturgical rites
• Liturgical Movement
• Roman Curia
• Eastern Catholic Churches

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• Vatican City
• Politics of Vatican City
• Economy of Vatican City
• Holy See – Soviet Union relations
• Pope Benedict XV and Russia
• Pope Pius XII and Russia
• Holy See – Russia relations
• Greece – Holy See relations
• Holy See – Romania relations

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• Protos
• Irenicism
• Full communion
• Communion of the Saints
• Greek East and Latin West

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Other

• The "Ravenna Document", at Vatican.va (The Holy See) - ECCLESIOLOGICAL AND CANONICAL CONSEQUENCES OF THE SACRAMENTAL NATURE OF THE CHURCH: ECCLESIAL COMMUNION, CONCILIARITY AND AUTHORITY. Ravenna, 13 October 2007.

Further reading

Orthodox

• Abbé Guettée (D.D.). The Papacy: Its Historic Origin and Primitve Relations with the Eastern Churches. Transl. from the French, with an introduction by Arthur Cleveland Coxe (Bp. of Western NY). New York; London: S Low, Son & Co.. 1867. 383 pp. (Also online here)
• Andrew J. Ekonomou. Byzantine Rome and the Greek Popes: Eastern Influences on Rome and the Papacy from Gregory the Great to Zacharias, A.D. 590-752. Lexington Books, 2007. 347 pp.
• Rev. Dr. Andrew Louth. Greek East and Latin West: The Church, AD 681-1071. The Church in History Vol. III. Crestwood, N.Y. : St. Vladimirs Seminary Press, 2007. 382pp.
• Aristeides Papadakis, (with John Meyendorff). The Christian East and the Rise of the Papacy: The Church 1071-1453 A.D. The Church in History Vol. IV. Crestwood, N.Y. : St. Vladimirs Seminary Press, 1994.
• Bishop of Nazianzus, Paul de Ballester. My Exodus From Roman Catholicism. Transl. from Greek by Constantine Zalalas. Bethlehem, PA: St. Nicodemos Publications. 2011. 144pp. ISBN 0-9831396-0-7
• Deno John Geanakoplos. Byzantine East and Latin West: Two worlds of Christendom in Middle Ages and Renaissance: Studies in Ecclesiastical and Cultural History. Oxford, B. Blackwell, 1961. 206pp.
• Dr. Clark Carlton. The Truth: What Every Roman Catholic Should Know about the Orthodox Church. Regina Orthodox Press, 2007. 268pp.
• Fr. Alexey Young. The Rush to Embrace. Nikodemos Orthodox Publication Society. 1996. 95pp.
• Fr. Dan Suciu. Orthodoxy: Catholicism Without Additions, Protestantism Without Subtractions. 36pp.
• Fr. John Meyendorff. The Primacy of Peter: Essays in Ecclesiology and the Early Church. St Vladimir's Seminary Press, 1992. 182pp.
• Fr. John Meyendorff. Rome, Constantinople, Moscow: Historical and Theological Studies. St Vladimir's Seminary Press, 1996. 201pp.
• Fr. John H. Erickson and John Borelli (Eds.). The Quest for Unity: Orthodox and Catholics in Dialogue: Documents of the Joint International Commission and Official Dialogues in the United States, 1965-1995. St Vladimir's Seminary Press (SVS) and United States Catholic Conference (USCC), 1996. 251pp.
• Fr. Laurent Cleenewerck. His Broken Body: Understanding and Healing the Schism Between the Roman Catholic and Eastern Orthodox Churches. Euclid University Press, 2008. 448pp.
• Irene Economides. Differences Between the Orthodox Church and Roman Catholicism. 16th Ed. Athens: Nektarios D. Panagopoulos, 2004. 112pp.
• Michael Whelton. Popes and Patriarchs: An Orthodox Perspective on Roman Catholic Claims. Conciliar Press, 2006. 177pp.
• Michael Whelton. Two Paths: Papal Monarchy - Collegial Tradition: Rome's Claims of Papal Supremacy in the Light of Orthodox Christian Teaching. Regina Orthodox Press, 2002. 215pp.
• Philip Sherrard. Church, Papacy, and Schism: A Theological Enquiry. Denise Harvey, 1978. 3rd. Ed., 2009. 134pp.
• Philip Sherrard. The Greek East and the Latin West: A Study in the Christian Tradition. Oxford University Press, 1959. Updated Ed., Denise Harvey, 2002. 222pp.
• Prof. Jοhn Ν. Karmiris. The Schism of the Roman Church. Transl. by Z. Xintaras. Theologia Review. Athens 1950, pp.400-587.
• Prof. Tia M. Kolbaba. The Byzantine Lists: Errors of the Latins. 1st Ed. Urbana and Chicago: University of Illinois Press, 2000. 248pp.

Articles

• Abp. Michael (Konstantinides) of America (1949-58). The Schism of the Roman Catholic Church from the Eastern Orthodox: 1054-1954. Orthodox Research Institute. 1954.
• Alexei Khomyakov. Essay on the Unity of the Church: The Church is One. In: W.J. Birkbeck, (Ed.). Russia and the English Church During the Last Fifty Years. Volume I. London: Rivington, Percival & Co. 1895. (Correspondence between William Palmer and M. Khomiakoff, in the Years 1844-1854)
• Archim. Augustinos Kantiotes. WHAT IS PAPISM? 1956.
• Bp. Hilarion (Alfeyev). Bishop Hilarion Alfeyev: Prospects of Orthodox-Catholic Relations. Orthodox Europe (DECR-MP). Paper delivered on 7 October 2002 at the University of St Thomas (St Paul, Minessota, USA); repeated on 9 October 2002 at the Catholic University of America (Washington D.C).
• Dcn. Herman Ivanov-Treenadzaty. The Vatican and Russia. Orthodox Life, Vol.XL, No.2 [March-April 1990], pp. 8-24.
• Deno J. Geanakoplos. The Council of Florence (1438-1439) and the Problem of Union between the Greek and Latin Churches. Church History. Vol.24, No.4. Dec., 1955. pp.324-346.
• Dr. Srdja Trifkovic. Shades of Grey: The Record of Archbishop Stepinac. OrthodoxyToday.org. June 8th, 2011.
• Fr. George Dragas. The Manner of Reception of Roman Catholic Converts into the Orthodox Church with Special Reference to the Decisions of the Synods of 1484 (Constantinople), 1755 (Constantinople), and 1667 (Moscow). Prepared for and read at the Orthodox/Roman Catholic Dialogue (USA) in 1998.
• Fr. Dr. Michael Azkoul. WHAT ARE THE DIFFERENCES BETWEEN ORTHODOXY AND ROMAN CATHOLICISM? The Orthodox Christian Witness, Vol. XXVII (48), Vol. XXVIII (6) and (8), 1994.
• Fr. Dr. Radu Bordeianu. "Orthodox-Catholic Dialogue: Retrieving Eucharistic Ecclesiology." Journal of Ecumenical Studies. 44.2 (2009): pp.239+.
• Hierodeacon Paul de Ballester-Convallier. Why I abandoned Papism. Kivotos magazine. July 1953, pp.285-291; December 1953 pp.483-485.

(Scroll down past the Greek section to get to the English version. Bishop Paul's article which explains why and how he was converted to Orthodoxy from Roman Catholicism. )

• John L. Boojamra. Athanasios of Constantinople: A Study of Byzantine Reactions to Latin Religious Infiltration. Church History. Vol.48, No.1. Mar., 1979. pp.27-48.
• Joseph L. Wieczynski. Khomyakov's Critique of Western Christianity. Church History. Vol.38, No.3, Sep., 1969. pp.291-299.
• Joachim Wertz. On the Serbian Orthodox New Martyrs of the Second World War: A Brief Historical Background. Orthodox Life, Vol.33, No.1 (Jan.-Feb. 1983). pp.15-22.
• Metr. Kallistos (Ware) of Diokleia. "The Ravenna document and the future of Orthodox-Catholic dialogue. (The 1983 Code of Canon Law: Twenty Five Years Later)." The Jurist. 69.2 (Summer 2009): 766-789.
• Metr. Seraphim (Mentzelopoulos) of Piraeus. Letter of Metropolitan Seraphim to Roman Catholic Bishop of Syros Island. November 9, 2007.
• Very Rev. Fr. Victor Potapov. Orthodoxy and Heterodoxy. Russian Orthodox Cathedral of St. John the Baptist. Washington, DC. 1996-1998.
• Very Rev. Leonid Kishkovsky. Primacy theme of Catholic-Orthodox dialogue. The Orthodox Church (News Magazine). Volume 43. Nativity/Theophany 2007.
• -----. Russian Orthodox Official Hopeful for a Prompt Beatification. A Great Pope, Bishop Hilarion Says of John Paul II. ZENIT News. 2005-04-05.

Heterodox

• Aidan Nichols (Order of Preachers). Rome and the Eastern Churches. 2nd Ed. Ignatius Press, 2010. 350pp.
• Abp. John R. Quinn. The Reform of the Papacy: The Costly Call to Christian Unity. Ut Unum Sint: Studies on Papal Primacy. New York: The Crossroad Publishing Company, 1999. 189pp.
• Cardinal Yves Congar. After Nine Hundred Years: The Background of the Schism Between the Eastern and Western Churches. Fordham Univ Press, 1959. 155pp.
• Cardinal Charles Journet. Exigences Chrétiennes en Politique. (First printed: Paris, Egloff, 1945). Editions Saint-Augustin, 1990. 590pp.
• Cardinal Walter Kasper (Ed.). The Petrine Ministry: Catholics and Orthodox in Dialogue: Academic Symposium Held at the Pontifical Council for Promoting Christian Unity. Transl. Pontifical Council for the Promotion of Christian Unity. The Newman Press (Paulist Press Imprint), 2006. 257pp.
• Dr. Stephen F. Brown and Dr. Khaled Anatolios. Catholicism & Orthodox Christianity. 3rd Ed. NY: Chelsea House (Infobase Publishing), 2009. 144pp. (ca. Grades 6-9)
• Dr. David Bradshaw. Aristotle East and West: Metaphysics and the Division of Christendom. Cambridge University Press, 2004.
• Fr. Dr. Adrian Fortescue. The Orthodox Eastern Church. 2nd Ed. London: Catholic Truth Society, 1908. 498pp.
• Jeffrey Bruce Beshoner. Ivan Sergeevich Gagarin: The Search for Orthodox and Catholic Union. University of Notre Dame Press, 2002. 321pp.
• Patriarch Maximos IV Sayegh (Melkite Greek Catholic Church, 1947-1967), Ed.. The Eastern Churches and Catholic Unity. Transl. John Dingle. Herder, Freiburg. 1963. 237pp.
• Prof. Henry Chadwick. East and West: The Making of a Rift in the Church: From Apostolic Times Until the Council of Florence. Oxford history of the Christian Church. Oxford University Press, 2003. 316pp.
• Prof. James Likoudis. Eastern Orthodoxy and the See of Peter: A Journey Towards Full Communion. Waite Park, MN: POS Inc., 2006. 174pp.
• Prof. James Likoudis. Ending the Byzantine Greek Schism: Containing: the l4th c. Apologia of Demetrios Kydones for Unity With Rome & the 'Contra errores Graecorum' of St. Thomas Aquinas. Rev'd Ed. Benedictus Books, June 1992. 231pp.
• Richard A. Mattiussi. The Ratzinger Formula: A Catalyst for the Unfolding Dialogue Between the Catholic and Orthodox Churches on “Conciliarity and Primacy”.
• Scott Butler, Norman Dahlgren, David Hess. Jesus, Peter & the Keys: A Scriptural Handbook on the Papacy. Queenship Publishing Co., 1996. 431pp.
• Stephen K. Ray. Upon This Rock: St. Peter and the Primacy of Rome in Scripture and the Early Church. Modern Apologetics Library. Ignatius Press, 1999. 331pp.

Articles

• Dr. Anthony Kenny. Follies of Roman Catholicism: How the Catholic Church failed to save itself from the Reformation. The Sunday Times (From The Times Literary Supplement). March 4, 2009.
• Blair Worden. "Pioneer for Unity: Metrophanes Kritopoulos (1589-1639) and Relations Between the Orthodox, Roman Catholic and Reformed Churches." The Journal of Ecclesiastical History. 41.3 (1990): p.524.
• F. Dvornik. The Photian Schism in Western and Eastern Tradition. The Review of Politics. Vol.10, No.3, July 1948. pp.310-331.
• Joseph A. Loya, O.S.A. Orientale Lumen Euro-East I Conference in Istanbul.(ECUMENICAL EVENTS)(Conference news). Journal of Ecumenical Studies 41.2 (Spring 2004). pp.287-288.
• Prof. Richard B. Rose. Church Union Plans in the Crusader Kingdoms: An Account of a Visit by the Greek Patriarch Leontios to the Holy Land in A.D. 1177-1178. The Catholic Historical Review. Vol. 73, No. 3 (Jul., 1987), pp.371-390.
• Fr. Dr. Russel Murray (OFM, PhD). "Mirror of experience: Palamas and Bonaventure on the experience of God--a contribution to Orthodox-Roman Catholic dialogue." Journal of Ecumenical Studies. 44.3 (2009): pp.432+.
• Sandro Magister. Ukraine an Obstacle to Catholic-Orthodox Unity. The Vatican Lobby. Thursday, July 1, 2010.