Atheists commonly assert that there is a profound dichotomy between faith and reason. This is exemplified by atheist evolutionary biologist Jerry Coyne ’s book Faith vs. Fact. He implies that we can have faith in the truth of something or we can have factual knowledge of the truth but we cannot have both. Faith and fact are, in his view, mutually exclusive. But that is not true.

Faith in God provides an indispensable foundation for the power of human reason. In the perspective proposed by medieval philosopher and theologian Thomas Aquinas (1225–1274), we must accept radical skepticism about the veracity of our perceptions and our concepts.

One may ask: how do we know that what we perceive or what we believe corresponds to reality? The answer is that we can’t know, in the sense that we can’t use our perceptive or intellectual abilities to prove the validity of our perceptions or concepts. To do so would be to reason in a circle. If our perceptions and our concepts are not reliable, then how could we use them to validate their reliability?

The skepticism Thomas requires is radical indeed. For example, even Descartes’s assertion, “I think therefore I am,” is not something we can prove without faith. The problem lies in the “therefore.” We must tacitly assume the validity of logic — specifically the logic of non-contradiction — to link “I think” to “I am.”

If we do not have faith in logic, then it would be possible to think but not to exist. Of course we find this possibility absurd, but it is only absurd because of our profound faith in the validity of logic — in this case, the validity of the logical principle of non-contradiction. That is the principle inherent in the belief that thinking presupposes the existence of the thinker. If logic were not reliable, there would be no logical connection between thinking and existence. Thinkers could think without existing.

So we are left with radical skepticism — theists and atheists alike. We can conclusively prove nothing about our knowledge of the world. It might all be a delusion and we have no certain way to be sure that it is not.

But of course sane people believe that — at least to some extent — we have access to truth. But this access is always a matter of faith — the validity of reason cannot be validated by reason itself. The process of this faith differs between those who believe in an omniscient and omnibenevolent God and those who do not.

I will speak here from the Christian perspective as it is the one with which I am the most familiar. The Christian has faith that he has access to truth because he believes that he has been created by a wise and loving God who guarantees this access to truth to him. Indeed this is a radical faith — we can be certain of nothing — but faith in God provides us with a coherent warrant to trust our capacity for reason. Christians have faith, and their faith makes a sensible and grounded belief in reason possible.

Atheists have just as much faith as Christians have — they believe that they have access to truth as well. But atheism provides no coherent warrant to trust the capacity for reason. In this sense, atheist faith is much more radical and much less coherent than the faith of Christians.

Christian faith in God provides a justifiable belief in the validity of reason. Atheist faith in the validity of reason is ungrounded and unjustifiable, and is therefore a much more radical and a much less credible faith.

We all lack a direct and self-validating knowledge of truth. Faith in God is the only coherent basis for trust in our capacity to know the truth. Atheist faith in the capacity to know the truth is incoherent.

Only atheist faith is opposed to fact; faith in God is the only reliable basis on which to trust our ability to know the truth. Thus, faith in God is the only coherent basis for reason.

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Excluding all reference to God from science is a form of theology It’s negative theology, to be sure, Michael Egnor and his guest Joshua Farris agree, but still a theology — and one with implications. The neurosurgeon and philosopher agree that excluding God from science provides an opportunity to make up all sorts of illogical ideas and call them science.