President Abraham Lincoln once said of the Know-Nothing Party, founded in 1844 and dissolved in 1860: “If the Know-Nothings get control, [the Declaration of Independence] will read all men are created equal, except negroes, foreigners and Catholics.”

The Know-Nothing Party dissolved in 1860, but its mix of nativism and white supremacy remained strong, and many of their proponents did not consider Catholics to be “white.” In fact, the Klu Klux Klan targeted my Catholic immigrant ancestors in the panhandle of Texas by burning crosses in their yards. My husband’s maternal grandmother in the same town told us of how her priest was tarred and feathered when she was a little girl. “He was never the same,” she said.

For most of my life these stories felt like ancient history. Sure, evangelicals would stop me and my friends in Colorado Springs when I was a teenager and try to “save” us, and sure, the evangelical megachurches in my hometown sent missionaries to other countries to try to convert Catholics because Catholics weren’t “saved.” But if anything, growing up in an evangelical town probably just made me more Catholic. We were all friends.

So Catholics who are unfamiliar with the theologies of Protestant denominations might be surprised to know that many reformed evangelical and fundamentalist churches, from the Missouri Synod Lutherans to the Seventh Day Adventists, still give credence to the idea that the pope (any pope, not just a bad one) is the Antichrist. Martin Luther himself taught this, as did John Calvin.

We may not know this because Catholics do not think about Protestants much and because by the time I was born in the 1980s, tensions between Protestants and Catholics in the United States had mostly eased. A once-unlikely political alliance of Catholics, evangelical Protestants and Mormons had formed around issues like abortion and homosexuality. Groups with different cosmologies but similar beliefs on sexual morality had found common cause under the banner of the religious right.

But that coalition now appears fragile, as some of the most prominent evangelical Protestant supporters of President Donald Trump sound a bit like the Know-Nothings of yore. At best, they want Catholics to be junior partners in their political movement; at their most intolerant, they envision a future America in which Catholic devotions and the devotions of non-Christian religions are illegal.

Of course, it is hard to know how seriously to take comments by Christian nationalist pastors like Doug Wilson, who leads a congregation in Moscow, Idaho, and the Communion of Reformed Evangelical Churches, as well as a publishing house, a video streaming service and an association of 170 classical Christian schools. Reverend Wilson has written, “A stout Protestant Republic could not allow a Virgin Mary parade” because it is “public idolatry.” It is unclear how folks like Reverend Wilson would ever be able to implement, let alone enforce, such fantasies. A religious procession, or “parade,” is protected under the First Amendment of the U.S. Constitution. But Wilson, and others like him, are postmillennialists, meaning that they believe they must get all the nations of the earth to practice their version of Christianity in order to bring about the second coming of Christ. Pete Hegseth, who leads the Department of Defense, is a member of Wilson’s denomination.

Not too long ago, even suggesting that “Catholic parades” should be banned would have been considered beyond the fringe of civil debate. But despite downplaying the horrors of slavery (writing, “the idea of the benevolent master is not a myth”) and suggesting the United States revoke women’s right to vote, Wilson was recently invited by Mr. Hegseth to lead a Christian prayer service at the Pentagon; he is also a popular speaker on the Christian nationalist circuit. 

Needless to say it’s clear that in Doug Wilson’s ideal America, Catholics would not be considered Christians.

And comments that would once have been considered uncharitable and uncivil—for example, the claim by Vice President JD Vance, himself a Catholic, that Catholic Charities is primarily motivated by its “bottom line” in providing humanitarian services for refugees—are now getting attention and being taken seriously by many voters.

Something else has changed. The Trump administration likes to punish critics and has violated civil norms by treating religious leaders and even the spouses of judges as if they were no more than political opponents. 

Consider that every pope in my lifetime has called for peace. St. John Paul II said, “The deliberate murder of the innocent is a grave evil always, everywhere, and without exception.” Pope Benedict XVI said, “The very name Benedict, which I chose on the day of my election…is a sign of my personal commitment to peace.” He explained: “I wanted to evoke both the Patron Saint of Europe, who inspired a civilization of peace on the whole continent, and Pope Benedict XV, who condemned the First World War as a ‘useless slaughter’ and worked for a universal acknowledgment of the lofty demands of peace.” 

Pope Francis said, “War is always, always, always a defeat.” But when Pope Leo similarly called for peace in the Middle East this past April, Mr. Trump wrote on Truth Social, “Pope Leo is weak on crime and terrible for Foreign policy.” This exchange followed months of Vatican criticism of Trump administration policies on immigration and the subsequent cancellation, in late March, of an $11 million-dollar federal contract with Catholic Charities to care for unaccompanied migrant children.

All of this feels new. Catholics are not in imminent danger of being arrested or oppressed—far from it. But we should take comments like Doug Wilson’s seriously because they represent a threat to the religious freedoms of all Americans. If Catholics can be retaliated against because their pope is teaching his religion, imagine what might happen to atheists, Muslims, Hindus, Buddhists or Jews.

We also know that figures once dismissed as fringe or “alt right”—like the Catholic provocateur Steve Bannon, who regularly called Pope Francis a “communist,” according to one of his former colleagues at Breitbart News—have gone on to positions of great power and influence, including as chief strategist and counselor to the president. Mr. Bannon also wrote to Jeffrey Epstein after he was arrested the final time, that we must “take down Pope Francis,” according to files released by the U.S. Department of Justice. 

Why would an American politician want to take down the bishop of Rome? Because it is necessary for Christian nationalist politicians to distance Christianity from its historical roots, from its first 1,054 years of well-documented Catholic and Orthodox teachings, if they want to remake it in service of their own goals.

Anna Keating writes and podcasts on Substack as “Inner Emigre.” She is also the co-author of The Catholic Catalogue: A Field Guide to the Daily Acts That Make Up a Catholic Life and is the Catholic chaplain at Colorado College in Colorado Springs.