I think from pure reasoning alone all an atheist could ever do is demonstrate why holy book X's god(s) doesn't/don't exist. I can't think of any argument from reason alone that would discard the possibility of a god. So I guess at most the theist could push for a Deist god but that's about it. Given that you call yourself a Christian though I think we might have some problems with the claims you want to attach to this plausible Deist god...
"It is the mark of an educated mind to be able to entertain a thought without accepting it" ~ Aristotle
