When I say that atheism is a kind of obliviousness to the obvious, I mean that if one understands what the actual philosophical definition of “God” is in most of the great religious traditions, and if consequently one understands what is logically entailed in denying that there is any God so defined, then one cannot reject the reality of God tout court without embracing an ultimate absurdity. This, it seems to me, ought to be an essentially inoffensive assertion. The only fully consistent alternative to belief in God, properly understood, is some version of “materialism” or “physicalism” or (to use the term most widely preferred at present) “naturalism;” and naturalism—the doctrine that there is nothing apart from the physical order, and certainly nothing supernatural—is an incorrigibly incoherent concept, and one that is ultimately indistinguishable from pure magical thinking. The very notion of nature as a closed system entirely sufficient to itself is plainly one that cannot be verified, deductively or empirically, from within the system of nature. It is a metaphysical (which is to say “extra-natural”) conclusion regarding the whole of reality, which neither reason nor experience legitimately warrants. It cannot even define itself within the boundaries of its own terms, because the total sufficiency of “natural” explanations is not an identifiable natural phenomenon but only an arbitrary judgment.

Naturalism, therefore, can never be anything more than a guiding prejudice, an established principle only in the sense that it must be indefensibly presumed for the sake of some larger view of reality; it functions as a purely formal rule that, like the restriction of the king in chess to moves of one square only, permits the game to be played one way rather than another. If, moreover, naturalism is correct (however implausible that is), and if consciousness is then an essentially material phenomenon, then there is no reason to believe that our minds, having evolved purely through natural selection, could possibly be capable of knowing what is or is not true about reality as a whole. Our brains may necessarily have equipped us to recognize certain sorts of physical objects around us and enabled us to react to them; but, beyond that, we can assume only that nature will have selected just those behaviors in us most conducive to our survival, along with whatever structures of thought and belief might be essentially or accidentally associated with them, and there is no reason to suppose that such structures—even those that provide us with our notions of what constitutes a sound rational argument—have access to any abstract “truth” about the totality of things. This yields the delightful paradox that, if naturalism is true as a picture of reality, it is necessarily false as a philosophical precept; for no one’s belief in the truth of naturalism could correspond to reality except through a shocking coincidence (or, better, a miracle). A still more important consideration, however, is that naturalism, alone among all considered philosophical attempts to describe the shape of reality, is radically insufficient in its explanatory range. The one thing of which it can give no account, and which its most fundamental principles make it entirely impossible to explain at all, is nature’s very existence. For existence is most definitely not a natural explanation phenomenon; it is logically prior to any physical cause whatsoever; and anyone who imagines that it is susceptible of a natural explanation simply has no grasp of what the question of existence really is. In fact, it is impossible to say how, in the terms naturalism allows, nature could exist at all.

These are all matters for later, however. All I want to say here is that none of this makes atheism untenable in any final sense. It may be perfectly “rational” to embrace absurdity; for, if the universe does not depend upon any transcendent source, then there is no reason to accord the deliverances of reason any particular authority in the first place, because what we think of as rationality is just the accidental residue of physical processes: good for helping us to acquire food, power, or sex but probably not very reliable in the realm of ideas. In a sense, then, I am assuming the truth of a perfectly circular argument: it makes sense to believe in God if one believes in the real power of reason, because one is justified in believing in reason if one believes in God. Or, to phrase the matter in a less recursive form, it makes sense to believe in both reason and God, and it may make a kind of nonsensical sense to believe in neither, but it is ultimately contradictory to believe in one but not the other. An honest and self-aware atheism, therefore, should proudly recognize itself as the quintessential expression of heroic irrationalism: a purely and ecstatically absurd venture of faith, a triumphant trust in the absurdity of all things. But most of us already know this anyway. If there is no God, then of course the universe is ultimately absurd, in the very precise sense that it is irreducible to any more comprehensive “equation.” It is glorious, terrible, beautiful, horrifying—all of that—but in the end it is also quite, quite meaningless. The secret of a happy life then is either not to notice or not to let it bother one overly much. A few blithe spirits even know how to rejoice at the thought.

Hart, David Bentley. The Experience of God (p. 16-19). Yale University Press. Kindle Edition.