Former President Donald Trump’s decision to dine at Mar-a-Lago with outspoken anti-Semite Kanye West and the even more virulent Nick Fuentes represents an inflection point, a new low in the mainstreaming of American anti-Semitism. It demonstrates, above all, the disturbing lack of leadership in the struggle against Jew-hatred and indeed all forms of hate. And, even worse, it emboldens extremists. Indeed, just days after the Mar-a-Lago dinner, both West and Fuentes went on conspiracy theorist Alex Jones’ “Infowars” show, with West praising Hitler and the Nazis, and outright denying the Holocaust. The mainstreaming of anti-Semitism has been well underway for...