In response to various currents within Protestantism to In 1920, the Patriarchal Locum Tenens, Dorotheus of Prusa, issued the Encyclical "Unto the Churches of Christ Everywhere"[http://incommunion.org/?p=142], which officially marked the entrance of Orthodox participation in the Ecumenical Movement. (See [[Ecumenism]].) The Encyclical, tied to the formation of the League of Nations and with that end in mind, gave eleven suggestions so "''that above all, love should be rekindled and strengthened among the churches, so that they should no more consider one another as strangers and foreigners, but as relatives, and as being a part of the household of Christ and “fellow heirs, members of the same body and partakers of the promise of God in Christ” (Eph. 3:6).''" (par. 6.) The first of the suggestions was "''By the acceptance of a uniform calendar for the celebration of the great Christian feasts at the same time by all the churches.''"

In 1923, a "Pan-Orthodox Congress" was held under the presidency of Meletios which comprised of members-- six Bishops, two laymen, and an archimandrite-- of a few of the local Churches (none of the members of the Pentarchy save Constantinople sent representatives). [[Anastasy (Gribanovsky) of Kishinev|Metropolitan Anasstasy Anastassy]] of the Russian Church Abroad attended its initial meeting, having been in the area, declared that the Synod had given him no instructions on the matter, and soon departed. In total, less than half of the local Churches were represented by so much as a layman. [http://www.orthodoxinfo.com/ecumenism/photii_2.aspx Photius of Triaditsa, "The 70th Anniversary of the Pan-Orthodox Congress", Orthodox Life, 1&2, 1994]. The purpose of the meeting was to implement the suggestions of the 1920 document, along with other uncanonical changes which were largely rejected, such as the elevation of married men to the Episcopate and the remarriage of widowed priests (sessions three and four). Finally, the Anglicans were present at the final meetings in the person of former Bishop Gore of Oxford, where it was decided that nothing stood in the way of reunion. In response, a five-member commission in Greece (of whom then Archmandrite-- and later Archbishop-- Chrysostom Papadopolous of Athens) determined to study the question of the use of the New Calendar and determined "''Not a single one of them [local Orthodox Churches] can separate from the others and adopt the New Calendar without becoming schismatic in relation to the others.''" (''Journal of the Government of the Greek Kingdom'', chapter 1, 24/25. 1. 1923, No. 8, see also ''OEM'', 1989, Chapter 17, p. 73, as noted in [http://www.orthodoxinfo.com/ecumenism/photii_2.aspx Photius].)