What is the religious significance of Constantinople the city founded by the emperor constatntine?

Answer 1

It became the center of the Eastern Orthodox Church.
Constantinople became the seat of Patriarch of Constantinople one of the four patriarchs of Orthodox Christianity (the others were the patriarchs of Alexandria, Antioch and Jerusalem). From the reign of Justinian the Great onward, the emperor , whose seat was Constantinople, were the supreme head of the Orthodox Church.

Answer 2

Constantinople originally was just the Capital of the eastern pert of the Roman Empire, even though Constantine built Christian churches there.

Over time, Constantinople became the main centre of Orthodox Christianity particularly after the fall of the western part of the empire and the surviving eastern part of the empire (which historians call the Byzantine Empire) became centered on Greece. The Hagia Sophia became the main church of Orthodox Christianity after Justinian I had it rebuilt in the 6th century AD (it had been destroyed during riots). The Hagia Sophia was the seat of the patriarchate of Constantinople, which over time became the most important one, especially after the fall of Antioch and Alexandria (seats of very important patriarchates) to the Arabs.

Answer 3

Constantinople provided easy trade and military access to the Mediterranean, Black Sea, Danube River, Dnieper River, and the land route to Turkestan and India.