According to all branches of Judaism, I’m Jewish because my mother was Jewish. I identify with a Jewish culture that values education, evidence, and questioning, which is why so many Jews like me become atheists.
My childhood Jewish juices flowed most deeply when anti-semitism was present. Having had relatives who died in the Holocaust, I was not about to give Hitler a posthumous victory by killing off my own Judaism when I became an atheist. Today the Holocaust is not an important part of the culture or memory for the millenial generation, which might partly explain why an increasing number of them don’t much value their Jewish roots.
Jewish sects run from most religious (Orthodox) to not-at-all religious (Humanistic), preserving Judaism through faith or culture. While I support Humanistic Judaism, I view it as a half-way house to John Lennon’s idealistic worldview where we imagine no religion. I like the universal message of Rabbi Hillel, when asked to recite the entire Torah standing on one leg: “What is hateful to you, do not do to your neighbor. The rest is commentary.” Comment, question, and argue, but be a good person.