I have lived for the last 3 years with two Phd philosophers as roomates, both in the last year of their dissertation at reputable institutions (Notre Dame, Penn/UIC respectively). They are both moderate semi-christian theists after having been fundamentalists as youths. I have a sceince and engineering background and am a naturalist atheist former JW. We have had most of the arguments theists and atheists can have (disregarding biblical issues / literalism which they agree is crap)...
1. Problem of evil...
2. Metaphysics of various forms...
3. Origin of the universe arguments...
4. Fine tuning / statistical improbability arguments....
and on and on.
In my opinion, arguments about metaphysics are the most troublesome to the uninitiated. This is perhaps based on my background. I tend to come out on top in the mathematics and science arguments.
To all the theists and atheists out there, what in your opinion is your / your opponents best argument?
Thanks!
(P.S. It's worth noting they both firmly believe in natural evolution with minimal divine involvement.)
(P.P.S. No YEC derailers, please.)