My entering class at Yale Law School in 2002 had one Jew who might be called “ultra-Orthodox.” He traveled some two hours to campus each Monday from Brooklyn, N.Y., and before the weekend, as far as I knew, he headed back. On Fridays when Sabbath came in early and he needed to get home, he could be seen racing white-faced for the exit, one hand pinning a velvet yarmulke to his head, the wheels of his tagalong briefcase crying out.

Yale Law School was about as secular a place as I had ever been—an institution where God seemed...