constantinople was not a religion but a city.
Christianity
Constantinople was based on the Christian religion and Rome was against it.
it was very much connected to religion.
The predominant religion in Istanbul (formerly Constantinople) today is Islam, with the majority of the population identifying as Sunni Muslims. However, there is also a small Christian minority, including Greek Orthodox, Armenian Apostolic, and Catholic communities.
The religion is one of those issues that is crucial, and that calls for trained ministering regarding
Christianity was the religion of Constantinople. The formed the Eastern Orthodox Church, attended it regularly, and had icons inside their house.
Back in the days of Constantinople, the Orthodox Church was highly involved in government and politics. Even though there was separation of Church and State, the Church exercised considerable influence in the government of Constantinople.
It was the Orthodox Church, or The Eastern Orthodox Church.
Yes Constantine created constantinople and completely re-shaped and institutionalised the religion to the point where he was lauded the 13th apostle.
Constantine's accomplishments were making Christianity the official religion of the empire & founding Constantinople (Istanbul).
Your question is very unclear. Constantinople was a Roman city, it was the imperial capital of the eastern part of the Roman Empire (the imperial capital of the western part of the Roman Empire was Milan).
Constantinople had pagan origins, but soon after the Edict of Milan, which established religious tolerance, the Christian Orthodox Faith started to become the main religion and lasted for over 1,000 years. After the conquest of Constantinople by the Ottoman Turks in 1453 AD, the main religion became Islam.