Yeah, almost all my Jewish friends and at least half of the "Muslim" ones - don't know if they'd always like that categorization themselves - are non-religious. No faith (or at least no faith matching the organized religion), just tradition and a rather small piece of that tradition-identity too.

On the other hand, I guess religious concepts in a way stick and shape society and citizens regardless of their faith. I'm a fourth-generation atheist but I suspect I do have some Lutheran concepts shaping me and guiding me. Atheist Protestant?