Oriental vs. Eastern Orthodoxy also seem to have different views on marriage. I understand that they are *not* the same thing, but unless I'm mistaken, Coptic Orthodoxy forbids divorce. Eastern Orthodoxy permits second and third marriages. Yet both are Apostolic. Multiple equally acceptable answers to a single question can be signs for some that everything being said can not be equally right.
If I may, as a member of the Church mentioned here, the Coptic Orthodox stance regarding divorce is not so much "opposing" the Eastern Orthodox stance (if we were that way, why would we allow Coptic-Greek intermarriage in the Patriarchal territory of Alexandria?), but recognizing the reality by which most divorces come: infidelity, in which one spouse is clearly at fault, or -- in an Egyptian specific context which I don't think has an analogue in much of the EO world -- the spiritual infidelity of conversion to another religion. (*ahem*)
Combine these factors with the aggressiveness of the Egyptian state in meddling in the Church's affairs in this matter (as it benefits the state-sponsored religion to have Copts turning to Islamic courts and Islam itself when the Church will not bless their infidelity; Islam, as I'm sure you know, is
very lax on both of these issues, having
divorce through talaq and fornication blessed through the example of Muhammad), and the reality of the situation really has more to do with the Church maintaining its autonomy and the inherent right She has to interpret Her own canons as is fit according to tradition and the needs of the believers than with anything that would judge whatever other churches are doing.
Heck, we are in communion with the Armenians, who are allowed to marry mainstream Trinitarian Christians like Catholics and Eastern Orthodox, while we can only marry Oriental Orthodox (with very few exceptions, as in the above example of Coptic-Greek intermarriage in Alexandria). I don't know what the Armenian Apostolic Church's canons say regarding divorce and remarriage, but it would not surprise me if they were more permissive than we are with regard to that too. If I had to guess, I would assume that surviving a genocide which slaughters 90% of your clergy and sends the majority of your people into a diaspora where they meet all kinds of different Christians probably has an effect on the kinds of allowances you're willing to make, but that's just a guess.
The point is: Please don't bring up the sad reality of the Chalcedonian/Oriental Orthodox schism as a point in favor of Catholicism. Catholics are also Chalcedonians (except for some renegade Maronites who know their history; haha), so I don't see how it can help.
And I'll state it outright here, as a member of one of the more conservative OO churches with regard to outsiders: In the modern day, at least since the time of the informal talks beginning in the 1960s, we have largely come to realize that we are much closer in an
ontological sense to the Eastern Orthodox than to Roman Catholics. Their way of being is closer to ours, albeit not the same. So I find it distasteful to be mentioned like this at that level, too.
So arguments for Roman Catholicism should be made from Roman Catholicism, not Oriental Orthodoxy.