i'd agree with redking about not placing religion in the equation.
for a simple reason.
one can speak to a religious person.
but the results are usually the following:
both agree to disagree (mature person)
one agrees to the other to get him to leave the other in peace.
the two argue until someone comes and stops them
one is an extremist and blows himself up with the infidels.
in the event that one wholeheartedly agrees with the other, either the religious type has "won" over a new faithful, other "atheism" claims a new pupil..
but usually both keep to their ideas until something Extreme happens (death of dear one, cancer diagnose, similar).
in which case an atheist usually becomes a faithful, and a faithful abbandon his god.
or otherwise they keep to their convictions.
this are all the possibilities i think.
the only thing to be pointed out is: everyone thinks with his brain, and with his brain does things... That's all there is. It's not god or the Force, or Satan, or anything which moves the humans hand. It's our neurons and our neurons work through electricity impulse. We might believe we do it for our free will, or for fate, or because god wants that, or anything of the sort, but in the end, we do what we do because we decide to do it. And then, only after we do it, we start saying we did it for a greater purpose, or for something else. (or just because we liked to change the colour of the walls)
it's better not to keep to religious matters, because they go sour quickly. Real quick.