Today, the typical Anglican is a middle-aged African woman. The burgeoning Nigerian church says it has 20 million Anglicans; Duncan believes it may have 25 million but perhaps chooses to underreport so as not to exacerbate tensions with Nigerian Muslims.

In London, more Muslims attend Friday prayers than Anglicans attend Sunday services. Last December, on the Sunday after former Prime Minister Tony Blair was received into the Catholic Church, more Catholics than Anglicans attended services in England, an increasingly common occurrence now, five centuries after the Reformation.

"I think," Duncan says, "the 21st century will be for the archbishop of Canterbury what the 20th century was for the royal family." That is, an era of diminution.

Because Protestantism has no structure of authority comparable to the Vatican, and because it does not merely tolerate but enjoins individual judgments by "the priesthood of all believers" concerning beliefs and obligations, all Protestants are potential Luthers. Hence it is evidence of spiritual vigor that Episcopalians in Quincy, Ill., and Fort Worth, Texas, will vote on disassociation from the U.S. communion on Nov. 7 and Nov. 14, respectively.

The Episcopal Church once was America's upper crust at prayer. Today it is "progressive" politics cloaked -- very thinly -- in piety. Episcopalians' discontents tell a cautionary tale for political as well as religious associations. As the church's doctrines have become more elastic, the church has contracted. It celebrates an "inclusiveness" that includes fewer and fewer members.