Exactly a month ago, I joined thousands from Britain’s Jewish community to march through London to draw attention to the rising tide of anti-Semitism – online, on our airwaves and on our streets. For all of us on that march, the terrorist attack on Heaton Park synagogue will have been shocking, horrific, heart-wrenching. But not surprising. Because in Britain, Jew-hatred has been mainstreamed. The people who were the victims of humanity’s greatest crime now fear for their lives on this country’s streets. After the Holocaust, the world swore never again. But it is happening again. Jewish undergraduates on campus are...