As white supremacists converged on a Charlottesville park for their violent “Unite the Right” rally, some of them menaced the city’s historic Beth Israel synagogue during Shabbat services, standing across from the building with semi-automatic weapons in their hands. “Had they tried to enter, I don’t know what I could have done to stop them, but I couldn’t take my eyes off them, either,” wrote Alan Zimmerman, the president of the Reform congregation, about the three neo-Nazis he stared down as congregants prayed inside. Zimmerman, in an essay published on ReformJudaism.org, said that neo-Nazis marching past the building shouted hateful...