Ultimately proving a god's existence is impossible. Also, please specify what you mean with "god" there are very many definitions of that word.
Remember during this discussion that faith is not about evidence. Faith relies on belief and you are allowed to believe whatever you want to. However, personally I consider religious people to be nuts as there is no reason to believe in such bullcrap.
Personally I'm agnostic/atheistic. I say that there is no way to prove or know of a god's existence and at the same time I don't believe in them. Especially not the Abrahamic religions, I deny the existence of the gods they describe.
