Occam's Razor, of course. This was a matter which had always bothered me, and I was thunderstruck when I read Hawking's suggestion. So it seems to me that unless you reject Occam's Razor, a rational approach to the question must lead one to conclude that there is no God. And that's why I'm an agnostic. In my opinion, faith is incompatible with reason.
Some people use faith in lieu of reason, and that's fine.
For instance, I have faith that my senses provide a reasonable accurate view of the world around me, within certain limits that everyone learns with experience. I also have a certain faith in my memory, although my faith in my short-term memory is somewhat lower, I think, than some peoples'. I'm forever going back to my apartment door to make sure I really did lock it, especially when I go to sleep. I could probably enumerate some other small faiths I have, but most of them are very basic things like senses and memory, and most of my other beliefs are founded on experience and logic resulting from those basic faiths. Obviously, faith works well for some people.