What is the Orthodox Church?
The Orthodox Church is the original Christian Church described in the pages of the New Testament. Her history, faith, and way of life can be traced in unbroken continuity all the way back to Christ and his Twelve Apostles.
The Greek word Orthodoxía comes from two words: orthós, which means straight or correct, and dóxa, from dokeín, which means opinion or belief. So ‘Orthodoxy’ simply means ‘correct belief’, and we use this word to distinguish the genuine unchanged faith from the various confessions that have changed or deviated from the original Apostolic teaching and tradition.
In other words, ‘Orthodoxy’ and ‘Christianity’ are synonyms. The Orthodox faith is the Christian faith revealed to mankind by God through the prophets and the Apostles, the Orthodox Church is the Christian Church founded by Jesus Christ. Thus, Orthodoxy is not an exotic variant of Christianity, not a conservative alternative to mainstream Christianity, not one Christian denomination among many, nor a particular cultural expression of Christianity — it’s Christianity, full stop.
What is meant by the term ‘Greek Orthodox’?
The term ‘Greek Orthodox’ — also ‘Roman Orthodox’ — refers to the particular liturgical tradition that developed in the Greek-speaking Eastern Roman Empire (as opposed to the Latin-speaking West). Greek Orthodox Christians, then, are those Orthodox Christians who worship according to the Eastern Roman (‘Byzantine’) rite.