BERLIN — An angry mob gathered on Berlin’s famed Kurfürstendamm avenue Thursday. Draped in Palestinian flags and shaking their fists in rage, they chanted in German, “Jude, Jude feiges Schwein! Komm heraus und kämpf allein!” (“Jew, Jew, cowardly swine, come out and fight on your own!”) Earlier last week in Dortmund and Frankfurt anti-Israel protester chanted, “Hamas Hamas Juden ins gas!” (“Hamas Hamas Jews to the gas!”). On Friday, a 200-strong mob in Essen chimed in, “Scheiss Juden!” (“Jewish shit”) This week, similar mobs gathered in Kassel, Nuremberg, Mainz, and other cities throughout Germany. The crowds are largely young, with...