During his first term as patriarch, Jeremias received a number of letters from the Lutheran theologians of the University of Tubingen that proposed union between the Orthodox Church and the Lutheran Church. This represented the first significant theological exchanges between the Orthodox and Protestants. The correspondence was initiated by a letter, delivered by Stephen Gerlach, the [[chaplain]] at the German Embassy to the Sublime Porte (Sultan’s seat of government), on [[October 15]], 1573. This event began an exchange of theological positions over the next several years. The letters in reply were written for Patr. Jeremias by his notary, Theodosios Zygomalas. At first, Jeremias’ replies were compilations of the Church Fathers and more recent writers. A second letter of [[September 15]], 1574, followed by a third dated [[March 20]], 1575 from Tubingen included a Greek translation of the “Augsburg Confession” and Greek translations of sermons by Jakob Andre, the chancellor of the University of Tubingen that defined the Lutheran creed. Jeremias’ reply of [[May 15]], 1576 summarized those points upon which there was agreement between the Orthodox and Lutheran doctrines and those on which there was no agreement, with explanations on the Orthodox views on each question. In the correspondence during the followings years until 1581 it became clear that the theological differences were not reconcilable and the correspondence came to an end.
Patr. Jeremias, as other patriarchs of the Ottoman era, was caught in the intrigues and politics that surrounded the Patriarchal office under the Ottomans. He came to the office after his predecessor, Metrophanes III, was removed from office, allegedly for pro-Roman tendencies and the desire of the Sultan to limit the duration of a patriarch’s time in office. Jeremias was replaced for a short period again by Metrophanes III before
himsef being re-elected a second time . Removed again after four years, he was again returned as patriarch in 1587.
With the issuance of a new civil calendar by a papal decree on [[February 24]], 1582 by Pope Gregory XIII, bearing his name, its consideration and rejection was the subject of three councils in Constantinople convened by Patr. Jeremias. The councils and principal members were: