I hope that some other members of the Fellowship will feel emboldened to join in this conversation. The questions which you raise are vital ones.
There is a level at which the obvious answer to the question of whether or not there was one particular group which was superior to the others should have been 'yes', with the words 'the Orthodox Church' following closely afterwards. Orthodox = 'right worship' - and that, surely, can come only from 'right belief'?
In 2 Thessalonians 2:9-15, St. Paul writes:
Quote:2:9 The coming of the lawless one is according to the working of Satan, with all power, signs, and lying wonders,
2:10 and with all unrighteous deception among those who perish, because they did not receive the love of the truth, that they might be saved.
2:11 And for this reason God will send them strong delusion, that they should believe the lie,
2:12 that they all may be condemned who did not believe the truth but had pleasure in unrighteousness.
2:13 But we are bound to give thanks to God always for you, brethren beloved by the Lord, because God from the beginning chose you for salvation through sanctification by the Spirit and belief in the truth,
2:14 to which He called you by our gospel, for the obtaining of the glory of our Lord Jesus Christ.
2:15 Therefore, brethren, stand fast and hold the traditions which you were taught, whether by word or our epistle.
For our purposes here the authorship of the letter is not strictly relevant (although it has always seemed to me unlikely that a congregation who had an authentic letter of St. Paul would be the obvious place to send a pseudonomous letter - but that's a different discussion); what is the text of the whole letter.
Here we see why 'right-belief' matters; the Thessalonians will be sanctified only through the Spirit and believing in the Truth; those who believe otherwise will perish; God allows those who wish to persist in error so to do; those who do not love the Truth which saves will not be saved. Now, to one who has always veered towards apocatastasis
such passages always have the effect of stopping me in my tracks; but it would seem here that St. Paul is talking about those who have been shown God's Truth and Grace and have rejected them; in that case it is man's free-will that condemns him to separation from God for, as we are told in John 3:16 and foll., it is God's desire that we should all be saved.
So there is a seeming paradox here with our generous Orthodoxy. It is right, proper, and our bounden duty, to bring the Word to all who will hear it; but there will be those who will not; or those who will pervert it and claim that theirs is the True Word. It is, in part, for this reason we need the Church; only through it can we have the assurance that we are not following the wrong path.
As you say, Christology is at the heart of our salvation, and this is one of the reasons St. Cyril of Alexandria spent so much time, energy and passion on the dispute with Nestorius; those who followed the teachings of the latter would not be saved - and that exercised St. Cyril greatly - as it should us.
Is this to argue that there is a 'common ground' upon which all Christians stand whether they know it or not? To be honest, I am unsure. When I was an Anglican I thought that what I believed was fully Orthodox. I had followed Newman through the Fathers but that road did not lead me where it led him; indeed, I am unsure it would have led him where it did after 1871. And yet, whilst what I professed to believe was Orthodox, it was not the fullness of Orthodoxy, and the Eucharistic encounter was quite different in kind.
The conclusion? I don't really have one - except to invite our fellows here to help us out.
In this is love, not that we loved God, but that He loved us and sent His Son to be the propitiation for our sins. (1 John 4:10)