Why do you believe in God or not?

"The whole world is made of incredibly tiny things, much too small to be visible to the naked eye - and yet none of the myths or so-called holy books that some people, even now, think were given to us by an all knowing god, mentions them at all. In fact, when you look at those myths and stories, you can see that they don't contain any of the knowledge that science has patiently worked out. They don't tell us how big or how old the universe is; they don't tell us how to treat cancer; they don't explain gravity or the internal combustion engine; they don't tell us about germs, or nuclear fusion, or electricity, or anaesthetics. In fact, unsurprisingly, the stories in holy books don't contain any more information about the world than was known to the primitive people who first started telling them. If these 'holy books' really were written, or dictated, or inspired, by all knowing gods, don't you think it's odd that those gods said nothing about any of these important and useful things?”
― Richard Dawkins, The Magic of Reality: How We Know What's Really True