[kosta50]

Hawthorn: Is it proper to speak of the Assyrian Church as “Eastern Orthodox?”

markomalley: Well, in terms of the Tetrarchy, they fall under the Patriarch of Antioch.

That makes them distinctly different than the Greeks or Russians, who fall under the Patriarch of Constantinople. But they are an Orthodox Church.

First of all, we don't "fall" under the Patriarch of Constantinople; we are in communion with him. He is not a "pope" jurisdictionally speaking.

Second, the Assyrian Church is Christologically gravely flawed, being Nestorian and is therefore not a "Church," but outside the Church.

[Cronos]

The Assyrian Church is not Eastern Orthodox, nor is it one of the Oriental Churchs (Armenian, Coptic, Ethiopian etc.). It is pre-Chalcedonian and, while it does date from the Nestorian schism, it is NOT a Nestorian Church -- kosta, the teachings of the Assyrian Church are based on Babai the Great and has been proven by them to NOT be Nestorian, but closer in line to orthodox teaching about the nature of Christ.

The split was due to two reasons: 1. Misunderstanding/Linguistic: while the most highly cultured parts of the Roman Empire spoke Greek, the Assyrian Church was NOT part of the Roman Empire, but was initially based in the Parthian (Irani) Empire, so there is evidence that the two sides just didn't understand each other.
2. Political: the moment the Parthians (Zoroastrians by religion) realised that they could split the Church from being a purely Roman Empire religion, to form their own Church that would owe allegiance to Parthia -- they leapt at the opportunity. Post the split with the Roman Empire based Christianity, the Assyrian Church (properly, the Church of The East) spread over all of Iran, Central Asia, Afghanistan, India, China, Mongolia -- there were even Mongol tribes that were Christian. This Church faced the most severest of persecutions: much more than any other Church, facing massacres at the hands of the Parthians, Tang dynasty China, the Arabs, the Turks, etc.