Jews and Judaism

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I was thinking the other day about how I got burned in a few places for suggesting that zionism is implicitly racist (which is not the subject of this post).

So: If being Jewish is not just a religion, but a cultural orientation (i.e. you can convert to Judaism and become a Jew), or a nationality (i.e. you can- exclusively- become an Israeli by being a Jew), or an ethnic minority (you can be born one and reject all other aspects of Jewishness but still be considered, by some, to be Jewish). Then, if no other nation-state or ethnicity, or religion in the world promotes this trinity of human phenomena; why should the Jews?

In my eyes Judaism is a religion, to be scorned as I scorn all god-botherers, irrelevant of the details of their superstition. From Mohammed to Thor to Isis they are all denying reason. So why is there such a thing as 'atheist' Jews? This is, to me, an oxymoron. I would like someone to explain it to me. I might go to Little Green Soccer Balls and ask them.