As I mentioned before, I have been learning about Ancient and Medieval Church history from the Covenant Theological Seminary. What has been so interesting to me is that Turkey is a real center for Christianity.
Paul spoke to the Ephesians in Ephesus (and his letter is in our bible now.) He also travelled to many other cities such as Perge, Derbe, Lystra, Antioch. John died in Ephesus. Peter built the first Christian church there in Antioch. Philip lived in Heirapolis, and was killed with him family there.
Constantine moved the capital to Constantinople, later named Byzantium, later named Istanbul. The Council of Nicea was in Turkey (and is now known as Iznik, between Bursa and Istanbul). As I previously mentioned Montanus lived in Turkey; Tertullian, author of the Trinity doctrine, spent time in Turkey and was a follower of Montanus. In short, Turkey was overwhelmingly Christian, and often was more important than Rome in influencing the direction of Christianity. Many of the greatest christian theologians either spent a great deal of time in Turkey, or were born there. Christianity was declared as the official religion in 380, during the reign of Theodosius I, and destruction of pagan temples was legalized.
Gradually, Christianity in Turkey disintegrated, so that when the Islamic Ottomans finally conquered the Byzantine Empire in 1453, it was inevitable that what had been a predominantly Christian region would be no more. In 1900, Turkey had a population that was 22% Christian. Today it is about 0.3%.
How could such an important center of Christianity change so radically?