Joel Simonds, a Los Angeles-based rabbi involved in progressive causes, has always known that many of his ideological allies did not agree with him on Israel. But after this weekend’s terror attack, the worst killing of Jews since the Holocaust, Simonds said many liberal Jews feel abandoned by people they thought were friends, some of whom have expressed little sympathy for the Israelis killed while focusing instead on the plight of Palestinians. “In these last few days, the silence is deafening and it is hurtful and a betrayal on so many levels,” said Simonds, the founding director of the Jewish...