Mark Byrnes is Associate Professor of History at Wofford College in Spartanburg, SC. 

Related Link The Founding Fathers debate about the possibility of a Muslim president

When asked on "Meet the Press" whether a candidate's faith should matter, Republican presidential candidate Ben Carson replied: "It depends on what that faith is. If it is inconsistent with the values and principles of America, then of course it should matter." He went on to say that he did not believe a Muslim should be elected president, and when directly asked if he believed Islam was consistent with the Constitution he replied: "No, I do not."

Critics understandably began to cite the Constitution's bar against any religious test for office. While this is of course an important point, it is not in fact directly relevant to Carson's comment. He did not say that a Muslim should be barred from running. He said that people should not vote for them, because, in his view, Islam is inconsistent with "the values and principles of America."

In this, Carson's comments evoke the history of anti-Catholic prejudice in America, particularly in the 1850s. The large number of economic refugees from Ireland in particular prompted fears that "Popery" was taking over America. The American Party (better known as the "Know-Nothings") is the most obvious manifestation of that fear. Its platform declared "War to the hilt on political Romanism" and "Hostility to all Papal influence when brought to bear against the Republic." They did not say Catholic immigrants could be barred from running for office. They did however pledge to never vote for anyone not born in the United States.

In both cases, religious belief is transformed into an anti-American, anti-democratic political belief, and all adherents of a faith are tarred with the same brush. After the liberal revolutions of 1848 in Europe, some American Catholic leaders (such as Orestes Brownson and Archbishop John Hughes of New York) denounced the revolutions. In that, they seemed to be following the lead of Pope Pius IX, who affirmed his opposition to "progress, liberalism, and modern civilization." Such sentiments convinced the Know-Nothings that Catholicism per se was incompatible with American values and principles. The Catholic Church, they thought, was itself a monarchy, and all Catholics therefore were suspect in their devotion to republican principles. Catholics owed unquestioning fealty to the anti-liberal Pope, and therefore could not be trusted to uphold the values and principles of America.

Today, of course, most Americans consider such ideas ludicrous. Catholic immigrants assimilated and became dedicated Republicans and Democrats. But in the 1850s, some Americans saw what today would be called "an existential threat" in the large number of Catholics entering the country. They represented an aggressive, anti-American religious faith that sought to convert the United States. In 1850, the Irish-born Archbishop Hughes was not shy about saying that this was, in fact, the goal:

“The object we hope to accomplish is to convert all Pagan nations, and all Protestant nations…. There is no secrecy in this. Our mission is to convert the world—including the inhabitants of the United States—the people of the cities, and the people of the country … the Legislatures, the Senate, the Cabinet, the President, and all!"

Imagine what Ben Carson would say about an American imam who said the same today.

Carson was not betraying an ignorance of the prohibition against a religious test in the Constitution. He was expressing something far worse: a bigoted anti-Muslim sentiment that echoes an earlier--and just as ugly--anti-Catholic bigotry.