Christianity in Turkey
Constantinople became established in the ecclesiastical hierarchy at the Council of Constantinople in 381. Second only to Rome, the legendary origins of the Patriarchate of Constantinople go back to St. Andrew, Metrophanes and Alexander of Constantinople. Constantinople's primacy over the Patriarchates of Alexandria and Antioch was reaffirmed at the Council of Chalcedon in 481, after which the papacy in Rome supported Constantinople in its dispute with Alexandria over monophysitism. Later, when Rome sought to assert its primacy over Byzantium, the Eastern Orthodox church developed the doctrine of pentarchy as a response.
Constantine the Great and Christianity
The accession of Constantine was a turning point for early Christianity. After his victory, Constantine took over the role of patron of the Christian faith. He supported the Church financially, had an extraordinary number of basilicas built, granted privileges (e.g., exemption from certain taxes) to clergy, promoted Christians to high-ranking offices, returned property confiscated during the Great Persecution of Diocletian, and endowed the church with land and other wealth. Between 324 and 330, Constantine built a new imperial capital at Byzantium on the Bosporos, which would be named Constantinople for him. Unlike "old" Rome, the city began to employ overtly Christian architecture, contained churches within the city walls, and had no pre-existing temples from other religions.