<i>Judaism – especially in this era, especially in the United States – is a cultural and ethnic signifier more than anything.</i>

I dunno. Probably less in this era, and less in the United States, than anywhere else in the world -- and than any other time.

The invention of Reform Judaism, which decided to redefine Jewishness as a "religion", but which only really flowered in the U.S., gets credit for that.

<i>what is judaism?It's not really a religion, since few believe in God and the afterlife really.</i>

Erm, it's a people, friend Torquemada. It's a bit rich to accuse Jews of not respecting the "religion" boundary, when that particular arbitrary category for organising how people organise their lives was invented by Euro-Christians well after the Jews had started up their thing.