Can the government in America force a Christian baker to design a cake celebrating a same-sex wedding? That’s the question before the U.S. Supreme Court Tuesday. The dispute in Masterpiece Cakeshop v. Colorado Civil Rights Commission comes on the heels of two other high-profile religious-freedom cases involving Christians— (2014), in which the court said a business couldn’t be forced to pay for contraception in violation of its owners’ religious beliefs, and Zubik v. Burwell, which effectively said the same thing about religious nonprofits, including the Roman Catholic order Little Sisters of the Poor.

This...