Two years ago, I published a book highly critical of religion, The End of Faith. In it, I argued that the world's major religions are genuinely incompatible, inevitably cause conflict and now prevent the emergence of a viable, global civilization.
In response, I have received many thousands of letters and e-mails from priests, journalists, scientists, politicians, soldiers, rabbis, actors, aid workers, students - from people young and old who occupy every point on the spectrum of belief and nonbelief.
This has offered me a special opportunity to see how people of all creeds and political persuasions react when religion is criticized. I am here to report that liberals and conservatives respond very differently to the notion that religion can be a direct cause of human conflict.
This difference does not bode well for the future of liberalism.
Perhaps I should establish my liberal bona fides at the outset. I'd like to see taxes raised on the wealthy, drugs decriminalized and homosexuals free to marry. I also think that the Bush administration deserves most of the criticism it has received in the last six years.
But my correspondence with liberals has convinced me that liberalism has grown dangerously out of touch with the realities of our world.
On questions of national security, I am now as wary of my fellow liberals as I am of the religious demagogues on the Christian right. This may seem like frank acquiescence to the charge that "liberals are soft on terrorism." It is, and they are.
A cult of death is forming in parts of the Muslim world - for reasons that are perfectly explicable in terms of the Islamic doctrines of martyrdom and jihad.
This is not to say that we are at war with all Muslims. But we are absolutely at war with those who believe that death in defense of the faith is the highest possible good, that cartoonists should be killed for caricaturing the prophet and that any Muslim who loses his faith should be butchered for apostasy.
Unfortunately, such religious extremism is not as fringe a phenomenon as we might hope. Numerous studies have found that the most radicalized Muslims tend to have better-than-average educations and economic opportunities.
Given the degree to which religious ideas are sheltered from criticism in every society, it is actually possible for a person to have the economic and intellectual resources to build a nuclear bomb - and to believe that he will get 72 virgins in paradise. And yet liberals imagine that Muslim terrorism springs from economic despair, lack of education and American militarism.
At its most extreme, liberal denial has found expression in a growing subculture of conspiracy theorists who believe that the atrocities of 9/11 were orchestrated by our own government.
Such an astonishing eruption of masochistic unreason could well mark the decline of liberalism, if not the decline of Western civilization. There are books, films and conferences organized around this phantasmagoria, and they offer an unusually clear view of the debilitating dogma that lurks at the heart of liberalism: Western power is utterly malevolent, while the powerless can be counted on to embrace reason and tolerance, if only given economic opportunities.
I don't know how many more engineers and architects need to blow themselves up, fly planes into buildings or saw the heads off of journalists before this fantasy will dissipate. The truth is that there is every reason to believe that a terrifying number of the world's Muslims now view all political and moral questions in terms of their affiliation with Islam. This may be the greatest problem facing civilization, and yet it is regularly misconstrued, ignored or obfuscated by liberals.
Liberals are rendering themselves increasingly irrelevant. Being generally reasonable and tolerant, liberals should be especially sensitive to the dangers of religious literalism. They aren't.
The same failure of liberalism is evident in Western Europe, where the dogma of multiculturalism has left a secular Europe very slow to address the looming problem of religious extremism among its immigrants. The people who speak most sensibly about the threat that Islam poses to Europe are actually fascists.
To say that this does not bode well for liberalism is an understatement: It does not bode well for the future of civilization.
Sam Harris is the author of The End of Faith: Religion, Terror and the Future of Reason. His new book, Letter to a Christian Nation, was published last month.