Because the capital of the Roman Empire was transferred from Rome to Constantinople in 330 AD.
The Ecumenical Patriarch (in Constantinople).
Constantinople was the capital of the Eastern Orthodox Church.
Jesus started the First Church which was the Catholic Church. Martin Luther started the Lutheran Church.
This is the name given to the Eastern Orthodox Church where the Ecumenical Patriarch resides in Constantinople (present-day Istanbul, Turkey). It is the church founded by St Andrew the Apostle, and was the Cathedral Church during the Eastern Roman or Byzantine Empire. It is similar to saying the papal church of Rome where the Pope resides. The Ecumenical Patriarch in Constantinople is known as the 'first among equals' in the Orthodox Church.
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.
The catholic church was never moved to constantinople, emperor constatine kept the church in Rome but moved the capitol to Constantinople. The SPRQ's belief of the church for salvation and emotional comfort kept the eastern empire alive for as long as it did, though it ultimately fell.
The Emperor
It was and is in Constantinople (Istanbul).
The Patriarch is the authoritative figure for The Greek Orthodox Church.
Princess Olga of Kiev was the first Russian leader to convert to Christianity. She was baptized in Constantinople into the Orthodox Church and is considered an equal to the Apostles.
Before protestants there were was one major christian church. It was just called The Church. Within that church there were 7 different branches (the biggest being Rome) that believed the same just different traditions and language. At the head of each of these branches was a group of bishops. Once or twice a year all the bishops of the different branches discussed religious matters about the church. But Rome was basically the highest of the 7. As time went on the Roman bishops wanted only one leader to lead the whole group that could communicate to God for them. The church closest to Rome was Constantinople. So Constantinople was the first to hear about there change. Constantinople excommunicated the Roman Church and the Roman church excommunicated Constantinople. So then there was just 5 churches. When the remaining 5 churches got word of what went on they brought back in the Constantinople church and they became the Orthodox church. And the Roman church turned into the Catholic church. So basically neither of us were really excommunicated but most people call this the first schism. and the second schism being the protestant. but looking at this subject there are many differant opinions
The Eastern Orthodox Church in Constantinople is called the Ecumenical Patriarchate, or is sometimes called the See of St Andrew (because it was founded by St Andrew).