The basis of all Orthodox Christology, Ecclesiology, and Soteriology is three-fold:
1) God is Trinity: One and Three simultaneously, in what is called the Hypostatic Union.
2) Jesus Christ is the second Person of the Holy Trinity, God the Son, Incarnate, that is, both completely God and completely human.
3) The purpose of all things is the communion between God and man, and we can partake of that communion only through communion with Jesus Christ.
The basic beliefs of the Orthodox Church are: 1) belief in Jesus Christ as the Son of God, Messiah, God and Saviour, 2) belief in the virgin birth of Christ and the Resurrection of Christ, 3) belief in the Blessed Virgin Mary (Theotokos) as the Mother of God, 4) belief in saints, angels and demons, 5) belief in baptism to become a member of the church, 6) belief in regular church attendance, 7) belief in regular Confession and Communion being essential, 8) belief in the seven Ecumenical Councils, 9) and acceptance of holy icons.
That He Is the Son Of God and Second Person Of the Holy Trinity.
They are called Eastern Orthodox Christians or just Orthodox Christians.
Eastern Orthodox is a branch of Christianity.
Your question is too general. There are many things that were not a cause of tension between these belief systems. The colour of my dog for instance
No, the Greek Orthodox church is a part of the Eastern Orthodox Churches.
greek orthodox
There are Eastern or Byzantine Rite Catholics but they are in full union with Rome as opposed to the Eastern Orthodox Churches which are not. There was a brief period in the 20th century, when a separate Orthodox Church broke away from the Eastern Orthodox Church in America and formed the America Orthodox Catholic Church. But it was yet another splinter of an already splintered Church. orthodox (small "O") means right belief, and thus is synonymous with Catholic. Now, there is also an Orthodox Catholic Church of America, also not in Communion with the Catholic Church. . You may read about the American Orthodox Catholic Church at the links below.
Anyone other than Eastern Orthodox eg Oriental Orthodox, Catholic, Protestant
Constantinople was the capital of the Eastern Orthodox Church.
18th Century Deism stressed morality and rejected the orthodox Christian view of the divinity of Christ
Russian orthodox. Greek orthodox. Coptic orthodox. Antiochia orthodox. Eastern orthodox. Ethiopian orthodox.
Eastern Orthodox