You're right, I don't have an answer as to how exactly the universe started. But just because the answer isn't known to science (yet?) doesn't automatically imply that the god must exist. Sure Christianity offers an answer to that question, but I just can't belive that one. As such I'm not
unwilling to accept God as the answer, but
unable to, since it just doesn't sound plausible to me. Being able to answer a question doesn't automatically make this answer true.
Note: I'm not an atheist but an agnostic, so I might not be the main target of this thread.

I don't absolutely rule out the possibility that there is some higher being, it's just that the explanation given by the bible (or any other holy book I've seen so far) seem unbelievable and in many occasions conflict with very plausible scientific theories.