To fully understand the NT, which I would think would be something all Christians, not just the Orthodox, would aspire to, the answer quite simply is yes, as Kosta so very completely explained. I cannot add to his post save to say that in Greek we still use letters for some numerical designations such as Α', Β', Γ' Δ', 1st, 2nd, 3rd, 4th. :)
To fully understand the NT, which I would think would be something all Christians, not just the Orthodox, would aspire to, the answer quite simply is yes, as Kosta so very completely explained.
In that case God's word, and indeed Christianity itself, is NOT transcendent. It is bound by the Greek. Please correct me if I'm wrong, but when you say "fully", I take that to refer (in part) to key differences in core theology. I disagree. God chose Greek as the original language for the vast majority of the NT fair and square. However, if we believe that Christianity is a revealed faith, then I can't accept that very important truths would lie buried only within the Greek. God already knew all about all the translations that were coming, and it doesn't seem consistent for Him to "hide" the real truth only within one language.
Of course knowledge of and study of the Greek is highly commendable and profitable for the understanding of scripture. Many people of varying Christian faiths have spent years in that pursuit. I just don't think that ALL Protestant translators throughout history were either liars or factually wrong. IOW, I do not think there is a monopoly on understanding Greek for only the followers of Apostolic faiths.