It’s easy enough to be in favor of a “nonsectarian” prayer before a legislative session — some invocation of a higher power that theoretically doesn’t exclude anyone (besides atheists, that is) — but what exactly does such a prayer sound like?

That was Justice Samuel Alito’s question during oral arguments at the Supreme Court Wednesday morning in the case of Town of Greece v. Galloway, and it got to the heart of the court’s basic discomfort with cases asking it to decide whether specific government-sponsored prayers cross the constitutional line and “establish” religion in violation of the First Amendment.

In Greece, a town of just under 100,000 in western New York, town officials invite local clergy to offer a prayer before monthly town board meetings. The prayers may technically be given by anyone, but for nine years they were exclusively Christian, many using language such as “in the name of the Lord and Savior Jesus Christ, who lives with you and the Holy Spirit, one God for ever and ever.” Two residents sued the town under the First Amendment.

Standing before the court, the residents’ lawyer, Douglas Laycock, suggested that a nonsectarian prayer would be satisfactory. Justice Alito wasn’t so sure.

“How could you do it?” Justice Alito asked. “Give me an example of a prayer that would be acceptable to Christians, Jews, Muslims, Buddhists, Hindus … Wiccans, Baha’i.”

“And atheists,” Justice Antonin Scalia added. “Throw in atheists, too.”

Mr. Laycock reminded the justices that atheists were already out of luck based on the court’s prior decisions. Then, riffling through his documents, he suggested, “The prayers to the Almighty, prayers to the Creator.”

“To ‘the Almighty,’” Justice Alito said skeptically. “So if — if a particular religion believes in more than one god, that’s acceptable to them?”

Justice Scalia, often impatient in religion cases, couldn’t resist. “What about devil worshipers?”

Over the laughter of the courtroom, Mr. Laycock said meekly, “Well, if devil worshipers believe the devil is the almighty, they might be okay. But they’re probably out.”

And so it went, the justices trying in vain to determine what sort of prayer, if any, would be sufficiently nonsectarian, and who should be responsible for making that determination. None of them seemed to relish the idea of playing at prayer editor.

As the argument progressed it was increasingly difficult to discern any grounds on which to justify legislative prayer other than the fact that it’s something we’ve always done — which was the basis for the court’s ruling upholding such a prayer in the Nebraska legislature in 1983, when it last considered the question.

Lawyers for the town leaned heavily on that ruling, but several of the justices seemed uneasy with its rationale. “The history doesn’t make it clear that a particular practice is okay going on in the future,” Chief Justice John Roberts said. “We’re not going to go back and take the cross out of every city seal that’s been there since, you know, 1800. But it doesn’t mean that it would be okay to adopt a seal today that would have a cross in it, does it?”

The question answered itself, and was a reminder of how much the country’s religious makeup has changed over the past two centuries. Justice Alito emphasized the point in returning to his earlier concern about workability. While the U.S. may once have been “98-percent-plus Protestant,” he said, today “there are all sorts of other adherents to all sorts of other religions. And they all should be treated equally, and — but I don’t — I just don’t see how it is possible to compose anything that you could call a prayer that is acceptable to all of these groups.”

Mr. Laycock agreed, and reached the inevitable conclusion to that argument. “We cannot treat everybody, literally everybody, equally without eliminating prayer altogether.”

But there is an alternative to “eliminating” prayer — a moment of silence, which is what the town of Greece did for years without complaint. It allows everyone to pray exactly as they wish; it even makes room for the atheists and devil worshipers.

For some — including several members of the current court — a “silence only” policy is surely a step too far. But it would be a reasonable compromise in a pluralistic society, and for justices who don’t want to become de facto prayer editors, it’s a bright line on an otherwise blurry canvas of conflicting tests and standards that have rarely satisfied anyone.