Any belief you hold about the potential of your brain must first be formed in your brain. If you believe your brain is capable of perceiving reality, your brain is telling you that. This is called "circular reasoning", no more logical than saying "the Bible is true because it says it is true."
If you believe your brain was designed by an infinitely wise and powerful God for the purpose of intelligent thought, you have very good reason to trust it. If, by contrast, you believe that it is the result of blind chemistry, you have no more reason to believe it is useful for intelligent thought than you have to believe a fried egg can produce an accurate map of the world. At the very best, you can say you have the ability to discover truths that prolong your reproductive potential.
In other words, when it comes to human reasoning abilities, the Christian worldview is internally consistent, whereas atheistic worldviews, particularly Evolution, are so weak that they don't even allow us to trust the reasoning process that would cause us to believe them! Only the Biblical worldview can fully account for our ability to reason, and it is therefore the only reasonable worldview.