For some time, author and pastor Tim Keller met regularly with a brilliant young scientist. This young man was haunted by the sense that God existed, but as he considered one argument for God after another, he ultimately found that every one of them was “rationally avoidable” at some point.¹

“I can’t believe unless I find at least one absolutely airtight proof for God,” said the troubled scientist.² On hearing this, Keller pointed out that he was assuming “strong rationalism,” and the scientist’s disquiet was somewhat settled when they realized that neither of them was able to give an airtight proof for that either.³

What this anecdote helps to illustrate is that we accept many of our most deeply held convictions as rational, even though we all admit that there are no noncircular arguments to justify them. Think, for example, of the widespread belief that there is a physical world very much like the one reported by our senses, or that there are minds other than our own.

This has led some philosophers to ask, “Do we need airtight proof in order to know that God exists?” As William C. Davis put it:

Critics of belief in God’s existence can insist that even if Christians think they have experienced God’s presence they can’t know that God exists unless they can prove it. But do these critics apply this prohibition to their own beliefs? If they did, then they would have to admit that they don’t know that tables and chairs exist, or that the world is more than five minutes old. These beliefs can’t be proven either, but it seems strange to insist that these are not things that we know.⁴

A Glimpse at the Clues for God

That said, multiple arguments have been advanced as evidence of God’s existence.⁵ None of them will represent convincing proof to every skeptic. However, when taken together, they merit careful reflection. As Tim Keller said of his conversations with the scientist, “We began to go back and review the lines of reasoning that he had been calling ‘proofs’ and began to look at them instead as clues. When we went about it with that perspective he began to see that, cumulatively, the clues of God had a lot of force to them.”⁶

With apologies in advance for necessary brevity, here are just a few of those arguments:⁷

1. The existence of something rather than nothing—that is, our very existence—is more likely if a creator exists than if one does not.
2. The universe is orderly to a remarkable degree, and in more than one way. (Natural laws are both simple and uniform, the capacity for reproduction is pervasive, and great complexity is produced using only a very small number of elementary particles interacting according to a small number of laws). Any one of these features suggests that it is more likely that the universe is the product of design than that it is the product of random forces impelling purposeless particles that resulted in accidental stability. Taken together, these two statements are even more formidable as an argument for a designer.
3. Value—both moral and aesthetic—appears to be an objective feature of the world (and not merely imposed by human preferences), a fact much more likely to be the case if a creator exists than if the universe is a grand accident.
4. Human consciousness and intelligence are more likely the products of a conscious and intelligent creator than of a physical universe devoid of either.
5. Humans have numerous features that are more easily explained by theism than by metaphysical naturalism, if only because metaphysical naturalism currently explains all human capacities in strict terms of their ability to enhance survival. Among such features are the possession of reliable faculties aimed at truth, the appreciation of beauty, and a sense of humor. Metaphysical naturalism also does not explain why humans possess (or at least convincingly appear to possess) free will.

Of course, it’s very possible to claim either that one of these five “features” of the universe doesn’t exist (as in the case of objective morality), or that natural forces can adequately account for them. However, as one author has noted, in none of these cases is it plausible to claim that naturalistic theories explain the data better than theistic ones. In each case, the hypothesis that God exists has superior explanatory power.⁸

Even the existence of suffering or evil (and our recognition of it as such) is better explained under the God hypothesis than under a naturalistic one. The philosopher Alvin Plantinga writes:

Could there really be any such thing as horrifying wickedness [if there were no God]? I don’t see how. There can be such a thing only if there is a way that rational creatures are supposed to live, obliged to live. . . . A [purely naturalistic] way of looking at the world has no place for genuine moral obligation of any sort . . . and thus no way to say there is such a thing as genuine and appalling wickedness. Accordingly, if you think there really is such a thing as horrifying wickedness ( . . . and not just an illusion of some sort), then you have a powerful . . . argument [for the existence of God].⁹

Weighing the Options

The existence of the universe as we perceive it is simply better accounted for when we allow for the possibility of God’s existence. Or, to paraphrase C. S. Lewis, many have come to believe in God for the same reason they believe the sun has risen: not just because they see it, but because by it they see everything else.