The "code" you refer to is not the sort of "code" that requires an intelligence to design it; natural selection takes care of that perfectly well. The "odds" are precisely what they ought to be to include "odds" in this discussion strikes me as peculiar, frankly, as it has no bearing...
I don't think I can say a great deal that hasn't already been said here by others, but my fundamental reason for disbelief is simply a lack of a proper reason. I have no reason to believe in a god, or gods, thus I do not. Simple as that. Well, not quite so simple as that (I have reasons...