My jewish atheist friend has an interesting theory on why so many jews in America *are* atheists. (I know there's something intrinsically confusing about labeling someone by a religion and non-religion.)
In America, Christians are the majority. As a Jewish kid, he felt like he was identified more for what he didn't believe - Jesus as the messiah - than what he did. From there, it was a short walk to atheism. Just thought this was a cool insight to share.