The dust of those doomed towers had barely begun to settle before some Americans began asking themselves who, beyond Al Qaeda, was really responsible. Suspects included the Jews (as usual), the sinister Bush White House, the complacent Clinton White House and, in the view of Jerry Falwell, God. It’s a tribute to the power of his imagination that, despite this strong competition, in “The Enemy At Home” (Doubleday, 333 pages, $26.95), Dinesh D’Souza has managed to come up with a startlingly original selection of fresh suspects ranging from Madonna to Robert Mapplethorpe’s awkwardly positioned whip. In essence, argues Mr. D’Souza, it’s the “depravity” (a word he savors with a little too much enthusiasm of our culture that has provoked a violent reaction among some fol lowers of Islam, and threatens to push large numbers of those he de scribes as “traditional” Muslims into the extremist camp.

Mr. D’Souza has long proved that he can be as skilled an observer as he is polemicist. The commentary in “The Enemy at Home” on atti tudes on the left about the Iraq war is thought-provoking, as is his as tringent criticism of the intellectu al confusion demonstrated by much of the right in the aftermath of September 11, 2001. Equally when we turn to Mr. D’Souza’s cen tral thesis, that both Western secu larism and its slutty handmaiden sexual permissiveness, threaten the sensibilities of at least some pi ous Muslims, he’s likely correct That may have been the case for a long time now (aggrieved mullahs have been raging about the wicked West for hundreds of years), but there cannot be much doubt these tensions have been exacerbated in recent decades. Thanks to cheap long-distance travel, the sinful infidel world is more accessible than ever before. And Muslims no longer even have to go to the mountain. Mass communication and the Internet have brought Britney, Lindsay, and the rest of the trailer park seraglio to communities where the teachings of the Prophet previously only had to compete with homegrown temptations. On a planet made small, civilizations may not necessarily have to clash, but they will certainly be forced to jostle.

Even if it’s clear that the hedonism of the West has contributed in some way to its current difficulties with the Muslim world, the size of that contribution is not. The primitive political structures and woeful economic underperformance that have characterized the Middle East for generations, not to speak of the resentment felt over Israel, have also played their poisonous and, I suspect, substantially more significant part. There’s also the delicate, not-supposed-tobe-asked question as to whether there is something built into the very nature of Islam that ensures that it will always, to borrow Samuel Huntington’s despairing phrase, have “bloody borders.”

Unfortunately, this is a question Mr. D’Souza doesn’t really put to rest. Instead, in his fawning, flattering portrait of a supposedly “traditional” Islam, he offers Americans possibly the most misleading depiction of an unfamiliar way of life since Margaret Mead returned breathless and babbling from Samoa. The reason that such a smart writer has chosen to take such a strange tack is, alas, all too obvious. He’s more interested in fighting the culture wars at home than confronting the global ideological challenge posed by Islamic extremism. In “The Enemy at Home,” Osama Bin Laden is reduced to little more than another stick with which Mr. D’Souza can beat those he considers to be our naughtier, more godless citizens: so not only is same-sex marriage a bad idea, but it will also bring the wrath of Al Qaeda crashing down upon our heads, and as for that pesky separation of church and state, well …

To say this line of reasoning is somewhat unconvincing is to be very polite, but even worse is the way it leads Mr. D’Souza to suggest that America should somehow attempt to keep “traditional” Muslims out of the extremist camp by doing what it can to stress this country’s own more socially conservative side. As propaganda distributed internationally, that might perhaps have some value. Sadly, Mr. D’Souza goes further than that, effectively arguing that the need to cultivate that traditional Muslim constituency of his is in itself a good reason for Americans to clean up their act at home. There’s a word to describe that type of logic. It begins with an “a,” ends with a “t” and is usually associated with a British prime minister named Neville.

But, as history shows us, there are some adversaries who can never be appeased. Mr. D’Souza may be conveniently vague about exactly what it is we are supposed to do to our lifestyle to win over our putative Muslim friends in waiting (Ban the bottle? Bring the burqa to Berkeley?), but he does find plenty of room for the grumbling and raving of one Sayyib Qutb. Poor, peculiar Sayyid Qutb, an Egyptian philosopher whose writings have been a major inspiration for many of today’s Islamic radicals, was disgusted by the “animalistic behavior” he claimed to have witnessed on a visit to America. That disgust clearly played a part in shaping his increasingly fundamentalist worldview, and Mr. D’Souza naturally sees this as important evidence in support of his case. In fact, it’s the opposite. Qutb’s visit to America took place in the Truman era, a time not usually remembered for its wild abandon. The event that appears to have shocked him the most was, wait for it, a church social.

You see, Dinesh, there really is no pleasing some people.

Mr. Stuttaford last wrote in these pages about the London Blitz.