I've seen a lot of my friends expressing surprise (or pride) at the recent survey result that atheists are more knowledgeable about religion than believers. This result held, as far as Pew could tell, even after controlling for levels of eduction.
A lot of factors go into this, of course. But I'd bet on one of the larger and more boring ones being that self-described atheists tend to think more about religion, on average, than believers. Plenty of people are just Catholic or Baptist or whatever by birth, go through the cultural motions, and don't really think about it. (My mom is this kind of Hindu.) As a mass cultural phenomenon, atheism is new enough that many percentage of its adherents embraced it themselves after personally exploring the issues. There's got to be a much lower percentage of first-generation Baptists than first-generation atheists, and the first generation is the one that cares.
I think this demographic explanation still leaves room for atheist triumphalism in the wake of the survey results.