Constantinople called Byzantium was founded as a Greek colony in the 7th century)' B. C. It was declared as the capital city by the Emperor Constantin in 330 A. C. As a New Rome. When the Empire was seperated into two parts in 395 A.D., the city became the new capital of the Eastern Roman Empire. This political status continued until the Ottomans conquered the city. Before the conquest, the Christian word was divided into two parts due to the polemics of Holy Spirit and hegemony of Po pe. This seperation deepened a lot during the 4th attack of the Crusaders. The efforts to unite the two churches failed before the conquest. Constantinople was conquered in I 453 by Fatih the Conqueror the famous Turkish Statesman. The conquest had great impacts on Christianity in different ways. Some of them have been positive and others have been negative. Positive impacts are as follows: The freedom of religion granted to the native Christian people, modernization of Greek Orthodox Church of Constantinople, establishing the Armenian patriarch of Constantinople, theological deepening in Orthodoksy. Negative impacts are as follows: Ending of Byzantium Era, hardening the seperation between Catholic and Orthodox religions, appearance of Moscow Churclı with claim to be the 3th Rome at the cost of a new seperation, Rome’s position under the threat of a possible Ottoman occupation