On Sunday, CNN’s Anderson Cooper asked Bernie Sanders whether he was intentionally downplaying his Jewish heritage. The socialist candidate, demonstrating just how much he cherishes faith, immediately politicized the topic: Look, my father’s family was wiped out by Hitler in the Holocaust. I know about what crazy and radical and extremist politics mean. I learned that lesson as a tiny, tiny child when my mother would take me shopping, and we would see people working in stores who had numbers on their arms because they were in Hitler’s concentration camps. Like Bernie, I grew up in a family with Holocaust...