U.S. House Speaker Nancy Pelosi just got a humbling lesson in the power of anti-Semitism: It can’t be bribed away with a plum subcommittee appointment or threatened out with a primary challenge. Watching the utter disaster that unfolded when congressional leaders suggested making a simple, full-throated condemnation of anti-Semitism, I tried to think of something less surprising. I couldn’t. This began bad for the Jews; it ended bad for the Jews; and in the middle was a whole heaping pile of bad for the Jews. Last week, after freshman Rep. Ilhan Omar, D-Minn., had made the latest in a series...