Robert S. Wistrich, who died suddenly last week, was considered the foremost scholar of anti-Semitism, which he called “the longest hatred,” one that appears to be metastasizing in the current era. Writing about Nazi anti-Semitism ruffles no feathers within academia and other elite circles. Mr. Wistrich, however, had been warning that “anti-Semitism has undergone a process of growing ‘Islamicization,’ linked to the terrorist holy war against Jews and other non-Muslims with its truly lethal consequences.” This “new” anti-Semitism,” he added, targetsIsrael, the only state with a Jewish majority: “the collective Jew.” “New” is a relative term: It was 40 years...