This is a question I've wondered about for a long time now. I decided to post this thread because i noticed that my sociology textbook says "all Jewish people share a common ethnicity". I don't buy this theory. As far as im concerned, Judaism is not an ethnicity, but a religion. This is why some Jews are dark and middle eastern looking while others have blonde hair and blue eyes. To say judiasm is an ethnicity is a bit crazy to me, because if you're Jewish but you don't believe in the religion, does that mean you still have to identify as Jewish? If a jewish person becomes Christian, are they still Jewish? I don't think so. What do you guys think?