It's always amusing to watch religious people tying themselves into knots trying to fit reality into their various belief systems. The problem with that (and why it's sorta fun to watch, for a while) is that the ONE thing that cannot be allowed to change is the belief system. Those who would argue that science is just another belief system need to understand that if true, then it's at least the only belief system that is flexible and willing to change in response to reality, rather than vice versa.
Anyway, it's pretty easy to logically disprove the concept of god as most religions seem to define him/her/it. Most religions, especially the abrahamic ones, state that god is all-loving, omnipotent and omniscient: he knows all, sees all and is all-powerful (and he loves us all too!) Wow, pretty cool god there. But, says a five-year-old child, if god's so great, why does he allow bad things to happen? Either he is omnipotent, and chooses not to do anything about "bad stuff", like preventing a flood that kills thousands, showing he's not all-loving, or he would do, but didn't know it was happening, showing he's not all-knowing, or did know about it, and looked on helplessly, showing he's not omnipotent. Or maybe god's just an asshole. Or maybe he doesn't exist. I know which conclusion I tend towards.