Anti-Semitism on the right and the left threatens to bring to a close an unprecedented period of safety and prosperity for Jewish Americans—and demolish the liberal order they helped establish. Stacey Zolt Hara was in her office in downtown San Francisco when a text from her 16-year-old daughter arrived: “I’m scared,” she wrote. Her classmates at Berkeley High School were preparing to leave their desks and file into the halls, part of a planned “walkout” to protest Israel. Like many Jewish students, she didn’t want to participate. It was October 18, 11 days after the Hamas invasion of southern Israel....
