He suggests that the other main line denominations differ from The Episcopal Church in that they have a more extensive history of breaking away and merging, and the idea that the Presbyterian Church USA (itself the result of merger by the Northern and Southern Presbyterians in 1983) is somehow a dog that didn't bark is misguided -- the Presbyterians, Baptists, Lutherans, Methodists, etc, are in constant flux. The Episcopal Church, on the other hand, except for the departure of the Reformed Episcopal Church in 1873, remained much more stable, and in fact as I've mentioned here, it managed not to split over slavery in the mid-19th century as many other Protestant denominations did.
Since I grew up in both the PCUSA (Northern) and PCUS (Southern) denominations, yes, I'm aware of that merger, though as the sources my correspondent cites indicate, the PCUS and PCUSA had been growing doctrinally closer for decades, and they both accepted the liberal National Council of Churches orientation of the main line denominations.
Still, the point I was making was that the "continuing Anglican" split is conventionally dated to the 1977 Affirmation of St Louis, which was specifically a result of TEC's ordination of women and the 1976 tentative revision of the Book of Common Prayer. There were earlier departures from TEC due primarily to its stand on Civil Rights, although my correspondent has been correct in emphasizing that those groups from the 1960s that later aligned themselves with the "continuum" were anxious to separate themselves from James Dees.
In fact, the earmarks of "continuum" doctrine from the Affirmation of St Louis to the founding of the ACNA in 2009 were specifically twofold: objections to the 1979 Book of Common Prayer and the ordination of women. My point about the Presbyterians -- and in fact, I think that can extend to all or most other main line denominations -- was that we had no equivalent movement there based on the ordination of women or liturgical modernization. There were certainly (and earlier) defections based on the general main line adoption of National Council of Churches liberalism, but that is not the same movement.
The breakaway Presbyterian groups my correspondent cites left that denomination either in the 19th century or earlier in the 20th century over different issues. (Princeton University, by the way, certainly up to its secularization the most prestigious Presbyterian school, did not admit African-Americans until the 1940s, an example of the social conservatism that motivated some Presbyterians earlier and not related to the issues that led to "continuing Anglicanism".)
It's also worth pointing out that among the dozen or more "continuing Anglican" groups that unanimously affirm the authority of the 1928 Book of Common Prayer and abjure the ordination of women, they seem remarkably fractious and disagreeable over many other, smaller issues of personality or liturgy. I would still say that the schism in The Episcopal Church is unique -- I'll certainly grant that TEC was in large measure cohesive until St Louis, although the actual relative numbers of "continuers" 1977-2009 also suggest that the movement has always been overrated (leaving the ACNA, which left over different, though perhaps even more vague reasons, aside).
The "continuers" are both a break from Episcopal and Anglican tradition, at least from the Restoration onward, and are also doctrinally unrepresentative of main line Protestantism from the 1950s onward.
