During Passover, Jews around the world gather to recount the story of the Exodus from Egypt. The Bible tells how God broke the bonds of slavery and punished the oppressor. His people were freed and then allowed to depart for a new land. This story has inspired liberation movements around the world, including the American civil-rights movement.

In the course of the Passover ritual, there is a famous song that recounts a long succession of miracles God performed for the Jews. After each comes the same refrain: “It would have...