Judaism it not a religion. It is a complex mix of culture, religion, language, history, nationality, and ethnicity each to varying degrees. Being a Jew is never predicated on what you believe, athiests and believers - traditionalists and liberals - are both jews to equal measure. There is such a hodgepodge of viewpoints and movements that you will not have to dig long before you find observant Jews who are skeptical about the existence of god - or most likely just don't bother with that question.