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.
Episcopal polity
Shortly after the Roman Emperor Constantine I legalized Christianity in 321, he also constructed an elaborate second capital of the Roman Empire located at Byzantium and renamed it Constantinople, in 324. The single Roman Empire was divided between these two autonomous administrative centers, Roman and Constantinopolitan, West and East, Latin speaking and Greek speaking. This remained the status quo through the fourth century. A deep chasm developed between the East and West, becoming critical around 350, known as the Arian, or Nicene controversy. The Eastern Christian Churches were thought by Constantine to believe against the Trinity; that Christ was lesser than God. Hilary, Bishop of Poitiers, France, believed that the Eastern Church should be given the opportunity to, at least, be educated on the subject. Constantine, in his wisdom, and upset by disagreement, banished Hilary to the East. Hilary perfected his Greek language skills while in exile, and determined the great divide between Rome and the East was actually not a disagreement at all, and was merely a linguistic ignorance on the part of his Latin speaking contemporaries. This truth became known in the West, though some differences lingered. Hilary of Poitiers later became St. Hilary, Doctor of the Church, for exposing the true Christian beliefs of the Eastern Church. Many of Hilary's writings were lost to time.