On 8 February 1364, Philotheus I was recalled to the patriarchal throne in Constantinople on the death of
Callistus I of Constantinople.
Relations with Rome Since 1354 the
Ottoman Empire had gained a foothold in Europe at
Gallipoli, threatening Constantinople from a new side. By 1362
Adrianople fell to the Ottomans and served as the forward base for Ottoman expansion into Europe. Threatened anew, John V Palaiologos appealed to the West for help in defending Constantinople against the Turks, proposing, in return, to end the
East–West Schism between Constantinople and Rome. In October 1369 John V, having travelled through
Naples to
Rome, formally converted to Catholicism in
St. Peter's Basilica and recognised the Pope as supreme head of the Church. Opposed to re-union on political terms, Philotheus I opposed these efforts by John V to negotiate with Popes
Urban V (1362–1370) and
Gregory XI (1370–1378). On the other hand, Philotheus I's second period as Patriarch was notable for his efforts to open sincere discussions with the
Roman Church to end the East–West Schism — not by diplomatic efforts like those of Emperor John V, who had just
abjured Orthodoxy for the Latin faith — but out of a real desire for a true and authentic union.
Synod in 1368 The authority of the Acts of the "
Hesychast Council" of 1351 were confirmed in the synod of 1368. The 1368 synod would be ranked as part of the
Fifth Council of Constantinople in 2016 by the
Council of Crete, thus granting it "universal authority" and Ecumenical status.
Relations with the Slavic Orthodox world Philotheus I also nourished a strong commitment to the unity of the Orthodox world in his second tenure, pursuing an ecclesiastical policy to organize the Orthodox churches of the Serbians, Russians, and Bulgarians, unto which hesychastic theology and spirituality spread. Secondly, the monastery's close links with Constantinople facilitated the spread of
Hesychasm to Central and Northern Russia. The act of excommunication of was revoked and the Serbian Church was recognized as a Patriarchate, under the condition of returning all eparchies in contested southern regions to the jurisdiction of the Patriarchate of Constantinople. In 1375 Patriarch Philotheus I consecrated
Cyprian as "Metropolitan of Kiev, Lithuania, and Russia" in the lifetime of
Alexius, the lawful incumbent of two of these three sees. The Russians felt deeply humiliated by this affront to their popular metropolitan, and the confusion ended only in 1390 when the Muscovites accepted Cyprian as
Metropolitan of Russia.
Writer and hymnographer Philotheus I was also engaged in writing a number of works setting forth the theology of the uncreated Energies and successfully taking issue with the humanist theologians who, in the works of Western scholastics, especially
Thomas Aquinas, found a
natural philosophy that enabled them to express their love of
classical antiquity to the full. Along with
Callistus I of Constantinople, Philotheus I was a Hesychast Patriarch of Constantinople, who used the
lives of saints to extol the ideal of
hesychia.
Exile and death In 1376, Patriarch Philotheus I was deposed by Emperor
Andronikos IV Palaiologos when the latter ascended to the imperial throne. Philotheus I reposed in exile in 1379. His tomb at the
Monastery of Akatalyptos Maria Diakonissa (Theotokos Kyriotissa) became a place of many miracles. == Legacy ==