Thank God for Hugh Hewitt. That’s one reaction we had to the Republican debate last night at Houston. It was Mr. Hewitt who finally cut through the quarrelling among the candidates and asked about the issue that, he said, keeps him up at night: “religious liberty.” We don’t mind saying that it keeps us up at night, too. It did so even before the death of Justice Scalia stranded the first right in the Bill of Rights precariously in the balance.

The answers Mr. Hewitt got struck us as underwhelming. It started with a question to Donald Trump about whether he’d make religious liberty “an absolute litmus test” for the Supreme (and other) courts. Mr. Trump said he would and then started attacking Senator Cruz for supporting the nomination of Chief Justice Roberts, who defaulted on Obamacare. Mr. Cruz blamed President George W. Bush and allowed that he would have elevated a different judge.

Mr. Cruz then noted that Mr. Trump once gave money to President Carter, Vice President Biden, Secretary Clinton, and even Senators Schumer and Reid. He suggested Mr. Trump would “look to cut a deal rather than fight for someone who won’t cut a deal on the Constitution.” Then Mr. Hewitt asked Mr. Trump whether he could be trusted on religious liberty. Mr. Trump complained about Mr. Cruz criticizing his sister, Maryanne Trump Barry, a United Sates Circuit Judge.

So Mr. Hewitt swung over to Senator Rubio. The Floridian said he doubted Mr. Trump would “replace Justice Scalia with someone just like Justice Scalia.” Mr. Trump then said he had great respect for Justice Scalia. “I thought he was terrific,” Mr. Trump said. Then he defended Planned Parenthood’s help to “millions and millions” of women while also asserting that he’s “totally against abortion.”

After which Mr. Hewitt turned to Governor Kasich and asked, “Can we trust you as much on religious liberty as the rest of these people?” Governor Kasich basically said no. He doesn’t favor same-sex marriage, he said, “but, look, the court has ruled and I’ve moved on. And what I’ve said, Hugh, is that, look, where does it end? If you’re in the business of selling things, if you’re not going to sell to somebody you don’t agree with . . .”

“OK,” he added, “today I’m not going to sell to somebody who’s gay, and tomorrow maybe I won’t sell to somebody who’s divorced. I mean, if you’re in the business of commerce, conduct commerce. That’s my view. And if you don’t agree with their lifestyle, say a prayer for them when they leave and hope they change their behavior. But when it comes to the religious institutions, they are inviolate in my mind, and I would fight for those religious institutions.”

This was a serious error on Mr. Kasich’s part. No one on that stage challenged him on it. The fact is that none of the key cases working their way through the courts involve individuals who won’t conduct commerce with individuals or couples because of their sexual orientation. The cake bakers, just to cite but one business being challenged, all are prepared to bake cakes for gay couples. What they’re not prepared to do is be coerced into expressing views with which they don’t agree.

Particularly views that violate their religious laws and beliefs. They wouldn’t do that for gay couples, and they wouldn’t do that for straight couples, nor does the Constitution permit the Congress or courts to require them to do so. More importantly, it’s not only “religious institutions” — to use Mr. Kasich’s phrase — that are covered by the First Amendment. It is also religious and non-religious individuals. Think about it this way: Can atheists be required to bake cakes praising God?

So the GOP debate in Houston passed as yet another event where an opportunity was missed for a real discussion among the candidates in respect of religious freedom and the Constitution. It is keeping millions awake at night. The failure of the candidates to engage on this crisis illuminates one reason why the Sun has been arguing for years for a debate among the candidates on the Constitution itself. It is, after all, the only thing the winner of the presidential election is going to have to take an oath to preserve, protect, and defend — so help him or her God.