@Humpleupagus @DireGoy As with most social issues, there are the two main dynamics at play.

The first is that they (and by they I basically mean anyone who grew up in the US, and west in general) learned to "punch up", which really means that they never learned to not be a bigot, but who you are not allowed to be a bigot against. You are not allowed to make fun of or attack Blacks on the basis of race, but Whites are fair game. It's okay to attack Christians, but not okay to attack Jews.

The other thing they learned is that it's a virtue to deconstruct social norms. Christianity is a social norm in the US, so it's fair to attack, but Judaism isn't fair since it isn't the norm.