Possible duplicate:
Often in debates about religion there seems to be an endless amount of arguments based on the presupposition of there actually being a god in the first place. (bible quotes cited as truths, anecdotes taken as evidence and such)
I would think a logical approach would be to check every argument against both the presupposition that there is, and that there is not, a god, and then see if there is sufficient evidence to conclude on one or the other. An aggregation of logical reasoning would at least then shed some light on the question.
So how does the presupposition of there being a god stack up aginst there not being a god?