In the case of Episcopalians like me (well, as I USED to be) there’s transubstantiation, which is the most important concept of all. No matter how different Episcopalian is from Anglican,
Episcopalian isn’t exactly different from Anglican, but these are “traditionalist” Anglo-Catholics. GKC can best tell you what traditionalist Anglo-Catholics think about transubstantiation, but generally I think it’s fair to say that their theology is essentially that of the Orthodox (i.e., they believe in what Catholics call transubstantiation but may not like to use the term), and their practice is the traditional practice of the Western Church (i.e., they reserve the Sacrament, celebrate Benediction, etc.) Such views do exist in the Episcopal Church as well, but the real hard-line Anglo-Catholics by and large oppose the ordination of women, so many of them left for groups like the TAC in the 70s, and many of those who didn’t have now left or are now leaving in the aftermath of +Robinson’s election.
My own rector from North Carolina (the parish where I was confirmed) is now a priest in the TAC (he and many of his parishioners left the Episcopal Church over a year ago, after I had already moved away). When I was in Journey in Faith (the Episcopal equivalent of RCIA), I remember thinking that what he was teaching sounded like transubstantiation, and asking how it squared with the 39 Articles (which officially reject transubstantiation). He responded that IV Lateran, being a council of the whole Western Church, trumped the 39 Articles, which were simply a statement of the Church of England and thus had to be interpreted in the light of more authoritative teachings. This is a good example of how Anglo-Catholics think.
One of the problems talking about Anglo-Catholicism is that broadly Anglo-Catholic rhetoric and liturgical practice has come to be the norm in the Episcopal Church. Most Episcopalians would claim, for instance, to be “Catholic” in some sense that Protestants as a whole are not–they may deny that they are Protestant, or they may claim to be a bridge church between Catholicism and Protestantism, or they may claim to be both Catholic and Protestant. Only the first of these is strictly Anglo-Catholic, but the general rhetoric comes from Anglo-Catholicism and relies on many of the arguments made by the ACs. So it’s easy for Anglo-Catholics to assume that Episcopalians as a whole agree with them more than they do, and conversely for non-Anglo-Catholics (whether Episcopalian, Catholic, or Orthodox) to assume that Anglo-Catholicism is just as vague and fuzzy as Anglicanism in general. This latter assumption is not entirely unfair, since there are degrees of Anglo-Catholicism, and even among the traditional groups who boast of Anglo-Catholicism you can find some people who (for instance) reject Marian devotion as un-Anglican, while others assume that it would be the norm for any true Anglo-Catholic. This is at the root of some of the divisions among “Continuing Anglicans.” However, the fact is that just because Episcopalians as a whole claim to believe in the “Real Presence” without specifying how their view relates to Calvinist, Lutheran, Orthodox, or Catholic versions of the doctrine does not mean that strict traditionalist Anglo-Catholics such as those in the TAC do the same thing.
There’s work to do in conversion and I have a hard time believing it can be done on the “group” or “express” basis!
The Pope has gone on record rejecting “ecumenism of return,” promising Protestants (and how much more Anglo-Catholics) that we can be reunited without giving up our particular traditions, and expressing a firm commitment to corporate reunion. I don’t think any of this has been said in such a way that you as a Catholic would be obliged to agree, but it’s worth noting that if you reject corporate reunion and insist on individual conversion you are disagreeing with your Pope.
Edwin