If your mind is only chemistry, why would you trust a single thing it tells you — including the belief that your mind is only chemistry?
Let me give the other side its best shot first, because a caricature is not worth refuting. Philosophical naturalism is the view that the physical universe is all there is — no God, no soul, no spirit, nothing above or behind matter and energy. Everything that exists is, in the end, particles in motion governed by physical law. It is a serious position held by serious people, and it has one great appeal: it promises a universe with no mysteries left over, everything explained from the bottom up.
Here is the problem. Follow naturalism all the way down and it quietly saws off the branch it is sitting on. It cannot account for the very thing you used to arrive at it: your own reason.
The argument in one uncomfortable question
On naturalism, your brain is a lump of matter assembled by unguided evolution. Every thought you have ever had is, at bottom, a chemical event — neurons firing according to physics, no more “true” or “false” than a rock rolling downhill is true or false. A rock does not reason. It just obeys the forces acting on it.
But if your thoughts are also just forces acting on matter, then the belief “naturalism is true” was not reached because it is true. It was produced because the atoms in your skull were arranged to produce it. And the atheist’s neurons and the believer’s neurons are equally just obeying chemistry. So on what ground does the naturalist claim his brain-state is the accurate one and everyone else’s is deluded? He has kicked away the ladder of reason and is now standing on air, insisting he climbed.
This is not a new trick of Christian debaters. It troubled honest naturalists themselves. Charles Darwin admitted it in a letter — what he called his “horrid doubt”: if the human mind developed from lower animals purely by survival pressure, could its convictions be trusted at all? Natural selection rewards survival, not truth. A belief that keeps you alive is not the same as a belief that is correct, and evolution has no way to tell the difference. So the naturalist is left trusting a truth-detector that his own theory says was never built to detect truth.
You cannot get an “ought” from atoms
The same crack runs through morality and logic. Reason runs on oughts: you ought to follow the evidence, you ought not to contradict yourself, a conclusion should follow from its premises. Those are not physical objects. You cannot weigh the law of non-contradiction or put justice under a microscope. They are immaterial, universal, and binding.
A universe of pure matter has no room for such things. Particles do not carry obligations. They do what the forces make them do. So when a naturalist appeals to logic to prove his case, or to justice to condemn something as evil, he is reaching for tools his own worldview cannot forge. He is borrowing from a moral and rational order he claims does not exist. The atheist has to sit in God’s lap to slap His face.
The self-refuting engine
Put it plainly. Naturalism is a claim made by reason that, if true, destroys the trustworthiness of reason. It is a thought that eats itself. To even argue for naturalism, you must assume your mind can track truth, that logic is valid, that evidence ought to be followed — and every one of those assumptions is a debt naturalism cannot pay.
This is why thinkers like C. S. Lewis and, in our day, the Oxford mathematician John Lennox have pressed the point so hard. Lewis put it with a scalpel: a theory that explained everything else in the whole universe but made it impossible to believe that our thinking was valid would be utterly out of court — for that theory would itself have been reached by thinking. You would have sawn off the branch you were sitting on.
What actually grounds a rational mind
So where do you have to stand for reason to work? You need a universe that is rational because it came from a rational Mind — a cosmos authored, not accidental. That is precisely the claim Scripture makes on its very first page and never lets go of.
“In the beginning was the Word, and the Word was with God, and the Word was God… All things came into being through Him, and apart from Him nothing came into being that has come into being.” (John 1:1-3)
The Greek word there is Logos — reason, word, the rational principle behind all things. John says the universe was not spat out by blind matter; it was spoken by a Mind. That is why science works at all: the world is orderly because it was made by an orderly God, and our minds can grasp that order because they were made in His image.
“God created man in His own image, in the image of God He created him; male and female He created them.” (Genesis 1:27)
There is your ground for trusting your own mind. You are not a lucky arrangement of chemicals that happened to start believing things. You are an image-bearer of the God who is Reason itself, given a mind meant to know what is true.
“…for by Him all things were created… He is before all things, and in Him all things hold together.” (Colossians 1:16-17)
The decision under the debate
Do not miss what this means for the honest skeptic. Every time you reason, argue, insist on evidence, or call something true, you are living as though the world is the kind of place the Bible says it is — rational, ordered, meaningful — and not the kind of place naturalism says it is. Your daily practice already contradicts your stated creed. You are a walking argument for the Author you are trying to reason away.
Romans says the evidence is not faint or far off; it is pressing in from every side, and the deeper problem was never a lack of proof:
“For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen, being understood through what has been made, so that they are without excuse.” (Romans 1:20)
So the question was never really whether you are smart enough to reason your way to God. The question is whether you will trust the Mind that made yours. The same Logos who spoke the galaxies and lit the fire of thought behind your eyes stepped into His own creation, went to a cross, and walked out of a grave — so that you would not merely reason about Him, but know Him. Your mind was His gift. He is asking for it back — not to silence it, but to give it, at last, something solid to stand on.
Teaching the Word. Watching the Times.
— SmithForChrist