EVERYONE, it seems, wants to get religion. Since the re-election of George W. Bush our magazines and newspapers have been playing catch-up, running long articles on the evangelicals and fundamentalists, an alien world the press typically ignores. Anxious Democratic strategists have issued pleas to find common ground with the religious center on issues like abortion, and elected officials have dutifully begun baring their souls in public. This is a media bubble, and like all bubbles it will burst. Far more interesting and consequential has been the effort to reinterpret history to give religion a more central place in America's past -- and, perhaps, in its future.

At the low end there is the schlock history written by religious propagandists like David Barton, the author of the bizarre pastiche ''The Myth of Separation,'' who use selective quotations out of context to suggest that the framers were inspired believers who thought they were founding a Christian nation. But there is also serious work being done by historians like Mark Noll and George Marsden to counter the tendency in American historiography to rummage through the past for anticipations of our secular, egalitarian, multicultural present. This is a useful corrective and reminds us that the role of religion in American life was large and the separation of church and state less clear than today.

At the highest end there has been a new scholarly look at the history of the modern political ideas that eventually put America on its special path. The best example is Gertrude Himmelfarb's important study, ''The Roads to Modernity.'' Here the argument is that, unlike the anticlerical philosophes of the French Enlightenment, the British and American thinkers of the 18th century looked favorably on religion as a support to modern democracy. They saw that it could assist in forming good citizens by providing moral education and helping people be self-reliant. By teaching people to work, save and give, religion could prove a ballast to the self-destructive tendencies of both capitalism and democracy. There is, therefore, nothing antimodern or even antiliberal in encouraging American religion and making room for it in public life.

As intellectual history, this is a sound thesis. It is, however, incomplete, which is why we should be wary of drawing contemporary lessons from it. In truth, the leaders of the British and American Enlightenments shared the same hope as the French lumières: that the centuries-old struggle between church and state could be brought to an end, and along with it the fanaticism, superstition and obscurantism into which Christian culture had sunk. What distinguished thinkers like David Hume and John Adams from their French counterparts was not their ultimate aims; it was their understanding of religious psychology. The British and Americans made two wagers. The first was that religious sects, if they were guaranteed liberty, would grow attached to liberal democracy and obey its norms. The second was that entering the public square would liberalize them doctrinally, that they would become less credulous and dogmatic, more sober and rational.

The first wager is well known, the second less so -- though it is probably the more important one. In fact, it is difficult to imagine the relative peace of American church-state relations without the liberalization of Protestant theology in the 19th century. ''Liberal'' in the theological sense means several things. It includes a critical approach to Scripture as a historical document, an openness to modern science, a turn from public ritual to private belief and a search for common ground in the Bible's moral message. Theological liberalism drew from many sources -- the English deists, Rousseau's romanticism, the philosophical idealism of Kant and Hegel. And thanks to Friedrich Schleiermacher and his 19th-century disciples it became the dominant school of Protestant theology, first in Germany, then in Britain and the United States. To many it appeared to fulfill the hope of a modern, reformed Christianity helping to shape citizens in modern, liberal-democratic polities.

But theological liberalism collapsed suddenly and dramatically in early 20th-century Germany, for reasons Americans would do well to ponder. The crisis was essentially spiritual but had wide political reverberations. Thinkers and ordinary believers began yearning for a more dynamic and critical faith, one that would stand in judgment over the modern world, not lend it support. They sought an authentic experience with the divine, genuine spiritual solace and a clear understanding of the one path to salvation. And what did liberal Protestantism teach? In the words of H. Richard Niebuhr, that ''a God without wrath brought men without sin into a kingdom without judgment through the ministrations of a Christ without a cross.'' And if that was the case, why be a Christian at all?

The carnage of World War I seemed to answer that question. The lesson drawn was that Christianity had been seduced by bourgeois, democratic society when it should have been bringing God's judgment down upon it. The liberal movement fell apart during the Weimar period, and from its ashes sprouted a wild array of religious tendencies, some ecstatic and mystical, some politically driven. Those who were politically engaged could be found all over the map, from the socialist left to the fascist right -- everywhere, it seemed, but in the liberal-democratic center.

If this story sounds somewhat familiar, it should. After the last Great Awakening at the end of the 19th century, liberal theology made steady gains in all the mainline American churches, and by the 1950's it represented the consensus within Protestantism, and was also softening the edges of American Catholicism and Judaism. Yet it, too, has now collapsed. Over the past 30 years we have seen the steady decline of mainline faiths and the upsurge of evangelical, Pentecostal, charismatic and ''neo-orthodox'' movements -- not only among Protestants but among Catholics and Jews as well. Politics played a large role in this, especially divisions over the Vietnam War and the cultural transformations since the 1960's. But the deepest dynamics were again spiritual.

It appears that there are limits to the liberalization of biblical religion. The more the Bible is treated as a historical document, the more its message is interpreted in universalist terms, the more the churches sanctify the political and cultural order, the less hold liberal religion will eventually have on the hearts and minds of believers. This dynamic is particularly pronounced in Protestantism, which heightens the theological tension brought on by being in the world but not of it. Liberal religion imagines a pacified order in which good citizenship, good morals and rational belief coexist harmoniously. It is therefore unprepared when the messianic and eschatological forces of biblical faith begin to stir.

The leading thinkers of the British and American Enlightenments hoped that life in a modern democratic order would shift the focus of Christianity from a faith-based reality to a reality-based faith. American religion is moving in the opposite direction today, back toward the ecstatic, literalist and credulous spirit of the Great Awakenings. Its most disturbing manifestations are not political, at least not yet. They are cultural. The fascination with the ''end times,'' the belief in personal (and self-serving) miracles, the ignorance of basic science and history, the demonization of popular culture, the censoring of textbooks, the separatist instincts of the home-schooling movement -- all these developments are far more worrying in the long term than the loss of a few Congressional seats.

No one can know how long this dumbing-down of American religion will persist. But so long as it does, citizens should probably be more vigilant about policing the public square, not less so. If there is anything David Hume and John Adams understood, it is that you cannot sustain liberal democracy without cultivating liberal habits of mind among religious believers. That remains true today, both in Baghdad and in Baton Rouge.