Encountering a pro-American European journalist who writes passionately and in chilling detail of the threat to the West from the rise of Islam in Europe, one is tempted to be supportive. But in her new book, “The Force of Reason” (Rizzoli, 307 pages, $19.95), Oriana Fallaci strains the good will of even the most sympathetic reader.

Never mind the eccentric way this volume has been published by Rizzoli, which seems not to have English language typesetting software in house. (In the first few pages of the book, both the words “have” – “have”- and “whore” – “who-re” – are hyphenated, as if they were being pronounced in a bad Italian accent.)

The more serious problem is the sweeping nature of her condemnation of Islam and Muslims. She faults them for the fact that “they breed like rats”; for requiring their meat to be slaughtered in a “barbaric” manner she says is similar to kosher butchery; for having their own schools, hospitals, and cemeteries; for immigrating; and for wanting accommodation of their religious holidays and Sabbath in schools and workplaces.

Much of her complaint about Islam, in other words, might as well be directed at Orthodox Jews, and a good deal of it at American Catholics. Ms. Fallaci’s cry of alarm – “Wake up, West, wake up! They have declared war on us, we are at war! And in war we must fight” – rings less alarmingly when it turns out that what she’s alarmed about is religions having their own cemeteries. Anyone familiar with the graveyard behind the Congregational church in any traditional New England town – or, for that matter, the Trinity Church graveyard in Lower Manhattan – realizes that, in itself, isn’t much of a threat at all.

Ms. Fallaci makes clear that her aversion is not to Islamist terrorism alone or to Islamic extremism but to Islam and Muslims in general. “Moderate Islam does not exist,” she writes, calling it “an illusion,” an invention of naive Westerners.

This is undermined at least in part by her own reporting, which includes an interview she had in 1975 with the Saudi oil minister, who offered her champagne from his cellar and invited her to accompany him to Mecca, notwithstanding the strictures of Islam against alcohol and against non-Muslims visiting Mecca.

As for Ms. Fallaci’s claim that “95% of Muslims reject freedom and democracy,” it’s just false, as demonstrated by the remarkable turnout in repeated Iraqi elections and in the fact that so many brave Iraqi troops have been willing to risk their lives and die fighting the insurgency there. They are fighting for precisely freedom and democracy.

For all these flaws, Ms. Fallaci’s book is an important one, because it illuminates a fundamental tension on the Western side of the war against the Islamist terrorists. American supporters of the war are led by a president who believes “freedom is not America’s gift to the world, it is the almighty God’s gift to every man and woman in this world.”

Yet in Europe, one of the most prominent spokeswomen for the war is Ms. Fallaci, who proclaims herself an atheist, insults the patriarch Abraham – “Who wants a Founding Father who is ready to slit his own child’s throat for the glory of some God?” – and manages to throw in insults to Mormons and Christian Scientists while she’s at it. Not to mention declaring the dogma of Mary’s virginity to be the formula of “a stupid brain.” One gets the sense at times that Ms. Fallaci’s opposition to Islam is just a subset of a broader opposition to all religion.

America allied itself with a godless Soviet Union back in World War II to defeat Nazism, then fought a longer battle to defeat the Soviet Union. If America’s Christian and Jewish right and the European secular left can hold it together long enough to beat back the Muslims at the gates of Eurabia, they seem headed afterward for a collision with each other. That, at least, was the implication I drew from Ms. Fallaci’s book.

The other implication – one that, in some of the book’s strongest sections, Ms. Fallaci herself concedes – is that it’d be a mistake to bet against the Western religions in that collision, if and when it ensues. For Ms. Fallaci herself is a complex figure on this front. She writes with apparent pride of her private audience with Pope Benedict XVI, a man she says she deeply respects since she read his “intelligent books.”

“In the Church of today I see an unexpected partner, an unexpected ally,” she writes. She has “faith” that the West “cannot lose” the war it is in, faith that comes from seeing New Yorkers braving the risk of a terrorist attack and gathering in Times Square on New Year’s Eve 2004 and shouting, she reports, “Hallelujah.” She refers to the Ten Commandments as “the genesis of our moral principles.”

Sometimes the atheist even goes overboard with her claims that “without the crucifix our civilization would not exist” and her rhetorical question, “Who, before Jesus of Nazareth, had ever blasted against slavery?”

Part of Ms. Fallaci’s atheism seems driven by the appeasement mentality that has afflicted elements of the Catholic Church, which, as she puts it disappointedly, “for the moment seems to be uncapable of defending Christianity.”

The title of this book is “The Force of Reason.” I’m all for reason – up to a point. Somewhere, though, in a book claiming the Ten Commandments are the genesis of our moral principles and that the basis of faith in a Western victory in the current war is a cry of Hallelujah, reason alone fails to suffice as an explanatory force. So perhaps the alliance between religious Americans and “secular” Europeans against Islamist terrorism will endure. Or perhaps when you get right down to it, not all the secular Europeans are as secular as they claim to be.