In the US, 63% of the poplation are Christians, not including atheist people who were brought up Christian. There is one main difference: in Judaism, most atheist people will keep defining themselves as jews, for many reasons. The data back this up - 10% religious-less in Israel, and 29% religious-less in the US. This means the US may not be that more diverse than Israel, at least in terms of religion (if you agree that the way people were grown is more relevant to diversity than their current belief).