It will be plain that Dennett's approach to religion is contrived to evade religion's substance. He thinks that an inquiry into belief is made superfluous by an inquiry into the belief in belief. This is a very revealing mistake. You cannot disprove a belief unless you disprove its content. If you believe that you can disprove it any other way, by describing its origins or by describing its consequences, then you do not believe in reason. In this profound sense, Dennett does not believe in reason. He will be outraged to hear this, since he regards himself as a giant of rationalism. But the reason he imputes to the human creatures depicted in his book is merely a creaturely reason. Dennett's natural history does not deny reason, it animalizes reason. It portrays reason in service to natural selection, and as a product of natural selection. But if reason is a product of natural selection, then how much confidence can we have in a rational argument for natural selection? The power of reason is owed to the independence of reason, and to nothing else. (In this respect, rationalism is closer to mysticism than it is to materialism.) Evolutionary biology cannot invoke the power of reason even as it destroys it.

Like many biological reductionists, Dennett is sure that he is not a biological reductionist. But the charge is proved as early as the fourth page of his book. Watch closely. "Like other animals," the confused passage begins, "we have built-in desires to reproduce and to do pretty much whatever it takes to achieve this goal." No confusion there, and no offense. It is incontrovertible that we are animals. The sentence continues: "But we also have creeds, and the ability to transcend our genetic imperatives." A sterling observation, and the beginning of humanism. And then more, in the same fine antideterministic vein: "This fact does make us different."

Then suddenly there is this: "But it is itself a biological fact, visible to natural science, and something that requires an explanation from natural science." As the ancient rabbis used to say, have your ears heard what your mouth has spoken? Dennett does not see that he has taken his humanism back. Why is our independence from biology a fact of biology? And if it is a fact of biology, then we are not independent of biology. If our creeds are an expression of our animality, if they require an explanation from natural science, then we have not transcended our genetic imperatives. The human difference, in Dennett's telling, is a difference in degree, not a difference in kind -- a doctrine that may quite plausibly be called biological reductionism.

Dennett is unable to imagine a fact about us that is not a biological fact. His book is riddled with translations of emotions and ideas into evo-psychobabble. "It is in the genetic interests of parents . . . to inform -- not misinform -- their young, so it is efficient (and relatively safe) to trust one's parents." Grief for the death of a loved one is "a major task of cognitive updating: revising all our habits of thought to fit a world with one less familiar intentional system in it." "Marriage rituals and taboos against adultery, clothing and hairstyles, breath fresheners and pornography and condoms and H.I.V. and all the rest" have their "ancient but ongoing source" in the organism's need to thwart parasites. "The phenomenon of romantic love" may be adequately understood by reference to "the unruly marketplace of human mate-finding." And finally, the general rule: "Everything we value -- from sugar and sex and money to music and love and religion -- we value for reasons. Lying behind, and distinct from, our reasons are evolutionary reasons, free-floating rationales that have been endorsed by natural selection." Never mind the merits of materialism as an analysis of the world. As an attitude to life, it represents a collapse of wisdom. So steer clear of "we materialists" in your dark hours. They cannot fortify you, say, after the funeral of a familiar intentional system.

BEFORE there were naturalist superstitions, there were supernaturalist superstitions. The crudities of religious myth are plentiful, and a sickening amount of savagery has been perpetrated in their name. Yet the excesses of naturalism cannot hide behind the excesses of supernaturalism. Or more to the point, the excesses of naturalism cannot live without the excesses of supernaturalism. Dennett actually prefers folk religion to intellectual religion, because it is nearer to the instinctual mire that enchants him. The move "away from concrete anthropomorphism to ever more abstract and depersonalized concepts," or the increasing philosophical sophistication of religion over the centuries, he views only as "strategic belief-maintenance." He cannot conceive of a thoughtful believer. He writes often, and with great indignation, of religion's strictures against doubts and criticisms, when in fact the religious traditions are replete with doubts and criticisms. Dennett is unacquainted with the distinction between fideism and faith. Like many of the fundamentalists whom he despises, he is a literalist in matters of religion.

But why must we read literally in the realm of religion, when in so many other realms of human expression we read metaphorically, allegorically, symbolically, figuratively, analogically? We see kernels and husks everywhere. There are concepts in many of the fables of faith, philosophical propositions about the nature of the universe. They may be right or they may be wrong, but they are there. Dennett recognizes the uses of faith, but not its reasons. In the end, his repudiation of religion is a repudiation of philosophy, which is also an affair of belief in belief. What this shallow and self-congratulatory book establishes most conclusively is that there are many spells that need to be broken.

'Breaking the Spell: Religion as a Natural Phenomenon,' by Daniel C. Dennett Leon Wieseltier is the literary editor of The New Republic.