How is being in an Apostolic Office different from being an Apostle?
I'm not being clear -- I apologize.
An office of Apostolic origin -- i.e., the Apostles began the practice of ordaining bishops to carry on the Good News, just as Jesus sent the Twelve. They had His authority, the bishops have theirs, etc.
I guess that brings me back to my original difficulty with were to put the end marker of which traditions are authoritative .
No traditions are authoritative. The Church is authoritative, and she preserved the Holy Tradition as the Apostles gave it to her.
But what if they were? Orthodox and Protestants often seem to wind up talking past each other precisely because we have these different understandings of what essential doctrines are.
I honestly don't know how to answer the first question without being flippant. But my first thought was "if a frog had wings......"
As to the follow-up statement, Orthodox and Protestants talk past each other in most instances because they are speaking different languages and coming from very different places. It's not so much a different understanding of essential doctrines (there is that, mind you), but it's more that there is a vast gulf of misunderstanding about what fundamental doctrines like atonement, sin, death, the resurrection, etc. mean. How they are interpreted. What the philosophical categories are and how they are applied. What the anthropology is. As hard as it was for me coming from a Lutheran background and having so much in common with the Orthodox worldview, I can't imagine coming from an Evangelical background. The Orthodox can -- literally -- say one thing and Protestants hear another. Then Orthodox look at the Protestants like "what?" And the Protestants are horrified that the Orthodox said something that doesn't fit their worldview, but fits perfectly within an Orthodox worldview.
Part of the problem is that Orthodoxy never really had to deal with Medieval Catholicism. Another part is Protestantism is basically a reactionary movement against Medieval Catholicism (painting with a broad brush here, but I can't think of a Protestant movement other than MAYBE high Church Anglicanism that doesn't fit this mold, and some would quibble with me excluding Anglicans). I don't really know the answer either. I do know this -- I heard from more than one person as we considered converting that the Orthodox believe we are saved by the merits of our own good works. That our soteriology is fundamentally Pelagian. Etc. And I didn't have to attend more than 2 or 3 Divine Liturgies to know that was a bunch of bull. It wasn't their fault -- they meant well, and they were merely reciting what they heard. But actually attending Orthodox services made it very, very clear this wasn't what was being taught at all. That's just one example, but I think it's a good one because it's so fundamentally opposed to Protestant notions of salvation to have good works as a significant part of the picture that when Protestants hear us talking about good works and how we have to do them and how fundamental they are to our salvation, they assume we mean that our good works merit salvation.
They don't realize that it's not "faith" that's missing from the equation, but "merits."