If your brain is just a swirl of atoms bumping into each other, why trust anything it tells you? That’s not a rhetorical question—it’s the fatal flaw at the heart of naturalism. In this article, I unpack the Argument from Reason, a devastating challenge to atheistic materialism famously advanced by C. S. Lewis. Drawing from Lewis, Paul Gould, and presuppositional heavyweights like Van Til and Bahnsen, I make the case that reason itself—your ability to think, reflect, and infer—only makes sense in a world created and governed by the God of Scripture. If you’ve ever wondered whether atheists can account for logic, or how to expose the internal contradiction of naturalism, this is where you begin.