"One Nation, After All," published in 1998, treated political attitudes. "Moral Freedom," which came out in 2001, focused on ethical issues. Wolfe completes the trilogy with his new "The Transformation of American Religion: How We Actually Live Our Faith" (Free Press).

Wolfe says most Americans are amiable souls in matters of religion, too, and that the powerful American culture sands down the rough edges of how believers behave, regardless of what official creeds might command.

As he and others have described it, American religion is generally individualistic, uninterested in doctrine, distrustful toward tradition and institutions, practical and "increasingly at home with the culture surrounding it."

His debatable conclusion: "American religion has been so transformed that we have reached the end of religion as we have known it."

There are exceptions. Mormonism manages to militantly preserve its beliefs and practices. And in terms of issues, Wolfe said in an interview, the harmonious landscape is marred by the raging debates over same-sex issues.

To a great extent, Wolfe is writing for fellow secularists, whom he depicts as frightened that their devout neighbors are undermining democracy. Yet he says liberals often rely on a "non-democratic institution," the courts, to limit public exercise of religion.

He says, "If anything, the problem American believers have is lack of confidence rather than excessive arrogance."

America has a propensity to reshape institutions to satisfy personal needs, Wolfe writes, and while this may be OK for consumer goods, it appears "out of place when matters of ultimate meaning and significance are at issue."

Many will doubtless dispute Wolfe's broad-brush theory, but he offers many keen observations.

And, intriguingly, he comes at all this as a religious outsider. Though Wolfe, 61, has directed his college's Center for Religion and American Public Life since 1999, he only began thinking seriously about the field in the late 1990s. The Philadelphia native says he underwent a pro forma bar mitzvah but was raised — and remains — a thoroughly secular Jew.

Conservative evangelicalism gets much of Wolfe's attention.

By Wolfe's reckoning, the culture has reshaped the evangelicals more than the opposite because they try so hard to appeal to the largest number of potential followers. He thinks U.S. evangelicalism is rarely sectarian. "Its problem, in fact, is the opposite — so strong a desire to copy the culture of hotel chains and popular music that it loses what religious distinctiveness it once had."

The faith makes few demands on the conscience or pocketbook. Fellowship and self-help trump doctrine and devotion. Though evangelicals believe they ought to present the Christian message to neighbors, they don't want to be offensive.

What about Islam? Here, too, Wolfe sees the beginnings of assimilation. For the first time, large numbers of Muslims are living in the within cultures they do not control. So, for instance, it is often impossible to observe daily prayers, and Wolfe considers it inevitable that they will face an intermarriage crisis like that affecting American Jews.