I ran across these recently, and I think they may be helpful, since most of the atheists around here are rationalists:
http://lesswrong.com/lw/3k/how_to_not_lose_an_argument/
http://yudkowsky.net/rational/virtues
http://lesswrong.com/lw/3k/how_to_not_lose_an_argument/
http://yudkowsky.net/rational/virtues
I'm not anti-Christian. I'm anti-stupid.