I have been an atheist since I was 15. I am now 26, and have read the full range of standard atheist arguments. The first one, which because it was first, probably had the most significant impact on me was George H. Smith's "Atheism: The Case Against God" which I purchased on Amazon along with Judith Hayes's "The Happy Heretic." I remember reading both books while thinking every page or two, "I considered this very point as I was losing my faith!" Later I read books by Dan Barker, Richard Dawkins, Christopher Hitchens, Sam Harris and so forth.
Each book was pretty much the same damn thing, but I loved reading them because I loved to see people in "my side" making such lucid, clear, wonderful arguments. I used those arguments when defending my atheist viewpoint to my friends. I don't seek out argument by any means, but I certainly welcome a debate when it comes my way. I think most people that join sites like ThinkAtheist are probably like me in this respect. I love nothing more than the opportunity to talk about religion, and I'm anything but religious.
I have noticed, as I see my new atheist friend's blogs, facebook posts, and twitter conversations, that they all crave this debate. One recent blog post was merely a two sentence invite to IM her and debate atheism vs. theism.
What is it about us that makes us crave the debate so much? What makes us read these books that merely reinforce what we already know? I love nothing more than youtubing a Christopher Hitchens slapdown just because it gives me goosebumbs and makes me feel good that there are people out there articulating the atheist argument with such brash eloquence. Maybe I am weird, but I don't think I am wrong.
Maybe our inquisitive nature - which made us atheists in the first place - makes us more predisposed to reveling in debates, arguments, disagreements, and defenses of our view. But that's just a theory. ;-)