Breaking the Faith.

• Author: Waldman, Steven

IT TOOK CENTURIES TO FULFILL JAMES MADISON'S UNIQUE VISION OF RELIGIOUS FREEDOM. DONALD TRUMP THREATENS TO UNDO IT.

American history is checkered with ugly bouts of religious persecution--from Protestant mobs burning convents in the 1830s, to Henry Ford publishing anti-Semitic propaganda in the 1920s, to anti-Muslim violence after September 11. But there was one thing that, until 2016, had never happened before in the history of our country. No one had ever won the presidency on a campaign that prominently and persistently attacked a religious minority.

As a candidate, Donald Trump didn't just demonize Muslims rhetorically. He offered specific policies that ran against our shared consensus about religious freedom. He proposed banning Muslims from immigrating to the country, claiming that Muslim refugees were "trying to take over our children and convince them how wonderful ISIS is and how wonderful Islam is." Just as stunning, Trump said he would "absolutely" require American Muslims to register in a special database to make it easier for the government to track them. Finally, he said that "there's absolutely no choice" but to close down some American mosques as a way of combating extremism.

Anti-Muslim animus grew as the 2016 election approached and Republican voters learned to take their cues from Trump. The percentage of Republicans who believed that at least half of Muslims living in the United States were anti-American jumped from 47 percent in 2002 to 63 percent in 2016, according to the Pew Research Center. Most shockingly, according to a Public Policy Polling survey, only half of Republicans were willing to say that Islam should be legal in America. So when Trump, a week after his inauguration, signed an executive order banning foreign nationals from seven predominantly Muslim countries from entering the United States, he was doing so with the overwhelming support of the voters who put him in office.

But then something encouraging happened. Thousands of people of different faiths flooded airports to protest the Muslim ban. The courts blocked the ban from taking effect, leading Trump to introduce what he called a "watered-down" version. Federal courts then blocked that one, too, because it still prioritized Christian refugees over Muslims. In June 2018 the Supreme Court's five conservatives upheld a third version of the ban, revised to drop the preference for Christians and add two token non-Muslim countries (including North Korea, which of course has never been a significant source of U.S. immigration).

The Muslim ban exemplified two facts about religious freedom in America: It is deeply baked into our system, cherished as one of our most sacred liberties. Yet it is also fragile. The consensus can unravel quickly.

On some level, liberals understand that this is a problem. But religious freedom is rarely top of mind on the left. To some degree, this reflects the right's success at casting religious freedom as a conservative issue--one that typically concerns expanding the role of conservative Christianity in the public sphere. It is also because the Democratic coalition includes more atheists and nonreligious people. But it's a mistake for liberals to ignore religious freedom. First, remember that the most successful progressive movements in history were driven in great measure by religion. Abolitionism and the twentieth-century civil rights movements were to a great degree religious crusades that drew power from their ability to use language and ideas that spoke to the fundamental beliefs of a broad range of Americans.

More important, when religious freedom collapses, it is the marginalized who suffer most. The moral commitments of liberalism thus require that the right to worship freely be defended. But in order to do that, we first need to understand the specifically American approach to religious freedom in America--an approach unique in the history of the world.

Societies have puzzled for millennia over how to have both religion and freedom. Today, most nations still have not found the right balance. More than three-quarters of the world's population lives in countries with limited religious freedom, according to Pew, and 42 percent of nations still have an official or preferred religion. Varieties of oppression have flowered: Eastern Orthodox Christians harass Protestants in Russia, Muslims persecute Coptic Christians in Egypt, Buddhists attack Muslims in Myanmar. Even Western democracies have stumbled, as when, in 2016, French policemen forced female Muslim beachgoers to strip off their head scarves and burkinis because their religious attire showed disrespect to secularism.

By comparison, the United States was, at least until the Trump presidency, managing its religious diversity well. America is home to 350,000 houses of worship, from Adventist to Zoroastrian, from urban storefronts to Christian megachurches that hold 40,000 people. Nearly three-quarters of Americans say they pray at least once a week. Notably, affluence has not dampened our religiosity as it has in other countries. The Pew Research Center recently mapped the relationship between wealth and religious practice. On the upper left of the chart is a cluster of countries that are religious and poor--Afghanistan, Nigeria, Guatemala. On the lower right are wealthy, secular nations, including Norway, Switzerland, and Germany. Way off by itself on the right edge of the chart is a single stray dot: the United States, wealthy and religious. America has reduced religious persecution without subduing religious passion.

But the struggle to make religious freedom real in America has been long and tempestuous. As with civil rights, the journey began with a set of ideas. The most significant visionary--and the most effective activist for religious liberty--was James Madison, who wrote the seminal treatise "Memorial and Remonstrance Against Religious Assessments," engineered the passage of the Virginia Statute for Religious Freedom, and guided the creation of both the United States Constitution and the First Amendment. More than anyone else, Madison devised the ingenious, counterintuitive, and often misunderstood blueprint for the religious liberty we enjoy today.

Madison's views were shaped by a shocking wave of religious persecution against Baptists near his home when he was a young man in Virginia. In 1771, in Caroline County, an Anglican minister approached the pulpit where Reverend John Waller was preaching and jammed the butt of a whip into his mouth. Waller was dragged outside and...