I’ve been doing a lot of thinking lately about the fascinating men and women of America’s founding generation. I want to share with you one of their stories.

Jonas Phillips was a penniless Jewish immigrant, an indentured servant, a hardworking businessman, and an American patriot who served in the Philadelphia Militia during the Revolutionary War. During the British occupation of New York, he snuck messages past the censors by writing in Yiddish.

Years later, Phillips addressed a letter to George Washington and the delegates at the Constitutional Convention.

He urged them not to include a religious test in the Constitution as a requirement for public service, because no man, he wrote, should be “deprived or abridged of any civil right as a citizen on account of his religious sentiments.”

Phillips wrote this letter because Pennsylvania, the state where he lived, required officials to swear that the New Testament was inspired by God. As a faithful Jew, Jonas Phillips could not do that.

“By the above law,” he wrote, “a Jew is deprived of holding any public office or place of government.”

Thankfully, Phillips’ letter—his prayer—was answered. Days earlier, the convention had voted unanimously to ban religious tests for federal office.

The language the Framers inserted into the Constitution was unequivocal: “No religious test shall ever be required as a qualification to any office or public trust under the United States.”

When the Founders wrote “ever,” they meant it.

I feel the need to stress this point because of the alarming behavior of some of my colleagues.

[On Wednesday], Notre Dame law professor Amy Coney Barrett came before the Senate Judiciary Committee. She had been nominated to be a circuit court judge. Her nomination has been endorsed by prominent legal scholars from across the political spectrum, including Neal Katyal, President Barack Obama’s acting solicitor general.

Nonetheless, at Ms. Barrett’s confirmation hearing a number of my Democratic colleagues insinuated that her Catholic faith would prevent her from applying the law freely and fairly.

“Dogma and law are two different things,” remarked one of my colleagues. “When you read your speeches, the conclusion one draws is that the dogma lives loudly within you. And that’s a concern.”

Another of my colleagues even asked Ms. Barrett to confess her faith under oath.

“What’s an ‘orthodox Catholic’?” this committee member asked. “Do you consider yourself an ‘orthodox Catholic’?”

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If these remarks had been some sort of bizarre aberration, I might have passed over them in polite silence.

But I feel compelled to speak out because I see a pattern emerging. A pattern of hostility toward people of faith who come before this body.

Just a few months ago, another eminently qualified nominee, Russell Vought, appeared before the Budget Committee to be considered for a post at the Office of Management and Budget.

One of my Senate colleagues used his time to question the nominee, not about management or budgets, but about his evangelical Christian beliefs.

“In your judgment,” asked this senator, “do you think that people who are not Christians are going to be condemned?”

Mr. Vought explained that he was an evangelical Christian and adhered to those beliefs.

But that wasn’t good enough for his questioner, who later stated he would vote against Mr. Vought’s nomination because he was not “what this country is supposed to be about.”

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These strange inquisitions have nothing to do with the nominees’ competency, patriotism, or ability to serve Americans of different faiths equally.

In fact, they have little to do with this life at all. Instead, they have to do with the afterlife. To my knowledge, the [Office of Management and Budget] and the 7th Circuit have no jurisdiction over that.

This country is divided enough. Millions of Americans feel that Washington, D.C., and the dominant culture despise them.

And how could they not, when they see their leaders sitting here, grilling patriotic citizens about their faith like inquisitors? How could they not feel like their values are not welcome in this chamber?

Religious freedom is of deep concern to me as a Mormon. My church has weathered extraordinary religious persecution, much of it sponsored by the government.

The first Latter Day Saints were exiled from home after home. In 1838, the governor of Missouri ordered that Mormons be driven from the land or “exterminated.”

Our first leader, Joseph Smith, once said, “the civil magistrate … should punish guilt but never suppress the freedom of the soul.”

That, of course, was before he was martyred by a bigoted mob.

Our country’s ban on religious tests is a strong bulwark for religious freedom. As an original provision of the Constitution, it predates even the Bill of Rights—and it applies not just to some religious adherents, but to all of them, equally.

The religious tests raised against Mr. Vought and Ms. Barrett do not favor one sect of Christianity over another, as was sadly common for much of our nation’s history.

Rather, they favor the secular, progressive creed clung to so confidently by the nation’s ruling elites. This creed has its own clerics, its own dogmas, and, as these nominees have discovered, it has its own heresies, too.

More and more, the adherents of this creed seek to use the power of government to steamroll disfavored groups—especially dissenters from their political dogmas.

So they force evangelical caterers to bake cakes celebrating same-sex marriages, as in the case that is before the Supreme Court now. And they force nuns to purchase contraceptive coverage. And sue religious hospitals that won’t perform abortions or sex-reassignment surgeries.

Yes, the secular, progressive creed has proven that it is capable of triumphalism and intolerance, just like the creeds that have gone before it. Not because its adherents are uniquely wicked. To the contrary—because they are human.

There is a way out of this vicious cycle of religious intolerance, Mr. President.

And that is for all of us to treat one another with civility and respect, while jealously defending the rights of conscience—for ourselves, our neighbors, and all our fellow citizens. For Christians, Jews, Muslims, atheists, and all others

This body can do its part by supporting legislation like the First Amendment Defense Act and the Marriage and Religious Freedom Act, which would protect people who have conscience objections to recent cultural changes.

But at a minimum, this body can do its part by respecting the constitutional rights of citizens who come before it. Lest we forget, we work for them, not the other way around. I trust my colleagues—Republicans, Democrats, and independents—will take this to heart.

Because religious freedom puts all Americans on the same footing. It helps men and women stand upright, honest before the law—and before God.

This commentary was adapted from Sen. Mike Lee’s recent speech before the Senate.