Our brain, and bodies, have evolved to help our species develop the behaviors that will help us survive. Beyond that, really, there is no certainty. We make judgments based upon what our senses tell us, and how our past experiences influence what we see. It can never be perfect.

And really, there is no way to prove whether God exists or not. That is a judgment you choose to make on faith. If it works for you, that’s all you need.