The term Orthodox Christianity may refer to:
* The Eastern Orthodox Church: the Eastern Christian churches of Byzantine tradition that adhere to the seven Ecumenical Councils, and are in full communion with the Ecumenical Patriarchate of Constantinople and with each other.
* The Oriental Orthodox Churches: the Eastern Christian churches adhering to the teachings of only the first three Ecumenical Councils (plus the Second Council of Ephesus).
* Eastern Christianity: Any Christian tradition tracing its origins to the East (the Balkans, Asia Minor, the Middle East, Eastern Europe, etc.) including the Eastern Catholic churches.
Eastern Orthodox Church Wikipedia Entry