Every event in the universe is causally linked to an event before it, right? And every one of those events are linked to prior events. These chains of events all converge and are set in motion by the initial event of the beginning of the cosmos. But what caused that event?

This is the infinite regress problem. The chain of causality in this cosmos of ours begs the question of its ultimate beginning. If our universe is cyclical, expanding in a big bang and then collapsing on itself only to then expand again, what started the cycle in the first place? And if there’s a multiverse spawning different universes, what set its spawning action into motion? Even if matter and energy were self-existent (which they are almost self-evidently not), it would be an inert existence, because no first motion, no first discrete cause can be self-existent. Besides the necessity of a Ground of Existence from which all contingent things (that is, simply all things) must partake of their existence, there must also be what Aquinas called an “Unmoved Mover” — the source of all derivative motion.

Classical theism calls this self-existent, self-moving reality God, not as a proper name per se, but simply as a moniker for the reality itself. It’s what Judaism, Christianity, Islam, and even some Vedanta Hinduism all have in common. Whether or how God may be personal, what characteristics he may have, and how he may reveal himself are all sources of disagreement between those creeds, but what they agree about is that there is one supremely self-existent One by which all creation comes into being. And again, not only does creation exist because of God, but creation also moves –is animated– because of God.

Against classical theism stands the creed of atheistic naturalism or materialism, which postulates a cosmos of nothing but stuff (matter and energy). Let’s remove a red herring here and note that this view isn’t synonymous with science, which is a methodological approach to discovering truth using only the tools of observation and mathematics. The glory of science is its self-imposed boundaries of testability and falsifiability. But atheistic materialism is a faith-based creed, built on the unfalsifiable assertion (and assumption) that there is nothing but matter, and matter that has been eternally in motion at that. That assumption is an ontological claim, not a methodological one, so it falls outside the realm of science. The inability of science either to prove atheism or to disprove theism makes it a neutral tool, not a secret weapon for or against either.

Science is left wanting of a reasonable naturalistic explanation for the beginning of our universe, because no observations or mathematics help us uncover its origin. We have fantastic models of the expansion of our universe in the billionths of a second after the initial event, but no real lead on what caused the event itself. There is no shortage of speculations by astronomers and physicists about what came before the big bang, but none of these are provable in any way and are therefore –as interesting and stimulating as they are– strictly unscientific. The question of ultimate beginnings must always be a philosophical one.

There’s a popular anecdote in which a Western explorer is told by an Easterner that his culture believes the world to be ultimately held up by a giant turtle. When the explorer asks the man what the turtle is standing on, he replies that he does not know. This, I believe, is a very sensible answer. He could have speculated that the World Turtle may be standing on the back of another turtle, but he would have had to accept an infinite regress of turtles on the backs of turtles in that case. The ridiculousness of an infinite stack of turtles with no bottom draws for us in stark imagery the real problem of the chain of material causality. Reason tells us that each discrete event must be caused by a previous discrete event, and so on ad infinitum. But in atheistic philosophy, in the materialistic cosmos, there is no bottom event. It’s turtles all the way down.

How could each discrete event have the necessary causal energy, the fertilitas, to bring another into existence without a primal, original energy energizing all the rest? How could each turtle hold up the next without a final ground for the bottom turtle to stand on? Materialism must reconcile itself to infinite turtles. Theists need not. The God of classical theism is exactly that ground under the turtles, the source of all fecund causality.

The atheist will rebut, “If God created the universe, what created God?” This question misunderstands the definition of God by placing him within the causal chain as one of the links in that chain. It assumes God to be just another turtle: “So what’s holding him up?”. But the definition of God as independently shared by every classically theistic creed is precisely that God is ontologically unique. God can’t be one of the things in a causal chain because God is no thing. He is, by definition, outside of time, space, materiality, and everything conceivable. He’s distinct from all things that exist, because he is existence as such. And as the Self-Existent, it’s only in him that anything can become anything, that what we call reality can gain its derivative, contingent existence. As David Bentley Hart writes, “No contingent reality could exist at all if there were not a necessary dimension of reality sustaining it in existence. And that is the dimension to which the word ‘God’ properly points.”

I’d wager that most people who espouse atheism are simply misinformed of the definition of God in the terms of classical theism. But there are those atheists who, fully understanding what’s at stake in rejecting a bottom to the stack of turtles, nevertheless go on saying that this is exactly what they believe. I again share Hart’s attitude toward this curious position: “I, at least, am willing to grant Naturalism its proper dignity as a kind of pure, unreasoning faith – absolute fidelity to an absolute paradox. Theism has nothing so magnificently wild and rhapsodically anarchic to offer. The faith it supports depends at some point upon a consistent set of logical intuitions, and so lacks the shear intellectual brio of that sort of madly, romantically adventurous absurdism. In a few of my more purely passionate moments, I find myself a little envious of materialism’s causal audacity and happy barbarism.”

It’s thrilling, I suppose, to think of oneself balanced on a stack of infinite turtles. But for me, the thrill is only imaginative. If for one second I believed it to actually be true, the dream would turn into a nightmare. I couldn’t find my balance in a reality which had no ground. I’m not saying I don’t believe there may be a stack of turtles beneath us; I just believe it must have a bottom.