Belief is a virus, and once it gets into you, its first order of business is to preserve itself, and the way it preserves itself is to keep you from having any doubts, and the way it keeps you from doubting is to blind you to the way things really are. Evidence contrary to the belief can be staring you straight in the face, and you won't see it... True believers just don't see things the way they are, because if they did, they wouldn't be true believers anymore.