How can people believe in a god?

It just doesn't make sense. Just look at how complex and amazing the human body is. Do you think this could just come from nowhere? Of course not! There had to be something responsible for its existence, and we know that was evolution. Religious folks think that something infinitely more amazing and complex and intelligent than a human being could just exist from nowhere and nothing, and make a universe. How can anyone possibly believe something so absurd? If a human being can't just exist from nowhere, then it's as clear as crystal that something smart enough to create a human being certainly can't either.