But Masterpiece has nothing to do with religious freedom. It’s about enshrining a freedom to discriminate. Historically, religious exemptions from the law have occasionally been granted to protect the person who holds the belief. But this case is different, in that it gives an individual the right to harm someone else. And that’s what the Masterpiece case is about: It would give individuals the right to discriminate.

It’s about landlords who could legally refuse to rent to someone because of who they are.

It’s about adoption agencies that could legally deny individuals and couples the right to have a family.

It’s about doctors who could legally refuse services to gay men and lesbians, or their children.

It’s about medical clinics that could refuse service to people who are H.I.V. positive. It’s about pharmacies that could legally deny birth control to single mothers or to anyone whose relationship the pharmacist might disapprove of.

Some of this havoc has already begun. In Mississippi, a funeral home refused to cremate a man’s husband once it learned the dead man had been gay. In Kentucky, a religious exemption law allows schools to bar L.G.B.T. youth from joining student groups.

Ironically, one group that might wind up discriminated against by the religious exemptions case is — wait for it — religious groups themselves. As one of the groups filing an amicus brief in the case points out, “petitioners’ arguments for a religious exemption permitting denials of service to same-sex couples could also be advanced to support denials of service to people of marginalized faiths.” The long bloody history of the world suggests that giving one faith permission to discriminate against another rarely ends well.

Finally, the court has already considered and rejected faith as justification for discrimination in a previous case. In the Piggie Park decision, the court rejected arguments almost identical to those being made now. That’s why the lawyers for Masterpiece will argue that Mr. Phillips’s cakes are artistic expressions and therefore protected speech.

Mr. Phillips certainly makes nice-looking cakes. But I’m not sure I’d call them artistic expressions, at least not in the same sense as, say, Joyce’s “Ulysses.” That argument demands that the court get into the business of defining art itself, a door the justices open at their peril. Is a well-manicured lawn a form of art by this definition? How about a lean corned beef sandwich? What would not be art if the court rules to protect icing and buttercream?