A District of Columbia Department of Transportation worker hangs the Vatican flag on Pennsylvania Avenue in front of the White House in preparations for Pope Francis's first official visit to the United States. Pope Francis will be arriving in Washington on Tuesday, and then will visit New York and Philadelphia. Anadolu Agency AFP/Getty

The members of Congress from decades past who felt at home bringing their anti-Catholic hatred to the House floor surely wouldn’t recognize their old haunts this week. On Thursday, a pope—known to them simply as the Antichrist—will address a joint meeting of Congress for the first time.

It’s not just that Pope Francis, the leader of the world’s 1 billion Catholics, will be the guest of honor on Capitol Hill. It’s that the longtime roost of Presbyterians, Methodists, and Baptists is now a very friendly place for Catholics, something that will be crystal clear to anyone tuning in to watch Francis’s address.

Seated behind the pontiff will be a Catholic vice president and a Catholic speaker of the House. Nearby will be the Catholic chaplain of the House. And escorting the pope to the rostrum will be the majority and minority leadership teams with Catholics as minority leader, majority whip, and Democratic caucus chairman.

It’s not much different out on the floor. When John F. Kennedy was elected as the first Catholic president in 1960, there were only nine other Catholics in the Senate; today there are 26—and 139 in the House. Then, there was one token Catholic on the Supreme Court; today six of the nine justices are Catholic and the Court includes not a single Protestant. Then, only one Catholic before Kennedy had ever won a major-party nomination for president or vice president; in the 2012 election, both vice-presidential nominees were Catholic. Additionally, seven of the current Republican candidates for president—Jeb Bush, John Kasich, Chris Christie, Rick Santorum, Marco Rubio, George Pataki, and Bobby Jindal—are Catholics.

It’s enough to make a bigot wistful for the good old days when prejudice need not be hidden. The explosion of anti-Catholicism was so virulent in 1928 that the White House Correspondents’ Dinner even featured a song making fun of it. That was the year New York Gov. Al Smith won the Democratic presidential nomination, the first Catholic to reach that height. In the Senate, Sen. Thomas Heflin of Alabama couldn’t take it.

“Wake up Americans,” Heflin declared in a passionate speech on the floor of the Senate. “Gird your loins for political battle, the like of which you here have not seen in all the tide of time in this country. Get ready for this battle. The Roman Catholics of every country on the Earth are backing his campaign.” He concluded that “they will lay the heavy hand of a Catholic state upon you and crush the life out of Protestantism in America.” Breaking with his party, he also told voters that if Smith became president, the pope would build a tunnel from Rome to Washington for the transmission of nightly orders.

He made such a fuss about the Catholic threat that another Alabama Democrat, state Rep. Lee Edmundson, submitted a resolution to name Heflin an admiral in the Navy and give him control of a new battleship to protect the country from a papal invasion. The resolution sarcastically declared the country “in grave danger of an attack by the pope of Rome.”

At that year’s Correspondents’ Dinner, the entertainers sang:

A vision of the future comes floating through my mind

St. Patrick’s Day in Washington in 1929.

Al Smith and all the Irish on parade with drum and fife

And Admiral Thos. Heflin a-running for his life.

Today, eight decades later, anti-Catholicism still is occasionally described as the last socially acceptable bias. But not in Congress. One obvious sign of how much it has changed since Heflin’s day is the fact that the chaplain of the House is, like Francis, a Jesuit. For the 211 years between 1789 and 2000, the job of chaplain was the province of Protestants—52 of them, including 16 Methodists, 15 Presbyterians, 7 Baptists, and 4 Episcopalians. When a Catholic came close in 1999, the then-speaker of the House—Dennis Hastert, a Methodist—balked. A search committee had recommended that he name a Catholic priest to the prestigious post. But he overruled the recommendation and nominated a Presbyterian.

The resulting uproar came at the worst time for Republicans, with their nominee for president, George W. Bush, on the defensive after an appearance at the virulently anti-Catholic Bob Jones University. It was Bob Jones Jr. who had greeted the 1978 death of Pope Paul VI by declaring, “Pope Paul VI, archpriest of Satan, a deceiver and an Antichrist, has, like Judas, gone to his own place.” With Republicans on the defensive in 2000 and the Catholic vote up for grabs, Hastert retreated and named a Chicago priest, the Rev. Daniel Coughlin, to the job. Coughlin held it until 2011 when Speaker John Boehner named the current chaplain, the Rev. Patrick J. Conroy.

Conroy will be watching when the pope makes history on Thursday. He probably won’t tell Francis how much anti-Catholic invective has been spoken from that rostrum over the past two centuries. But at least one of the predictions of the bigots has come true, a fact noted by President Jimmy Carter when John Paul II made the first-ever papal visit to the White House in 1979.

On that day, Carter, a devout Southern Baptist, recalled the nation’s long history of prejudice against Catholics and the attacks against John F. Kennedy when he ran for president. There were, Carter later recalled, “allegations that if he was elected, the American people would see the pope in the White House.” He added, “When I introduced John Paul to some visiting congressmen, I pointed out that the predictions of the Protestant protesters ... had finally come true.” And it didn’t take a tunnel.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.