This article needs more citations. (December 2021) |

Romanism is a derogatory term for Roman Catholicism used when anti-Catholicism was more common in the United States.[citation needed]
The word was first attested in 1603. The Fundamentals, often seen as the foundation of Christian fundamentalism, saw "Romanism" as the "single greatest threat to authentic Christian faith" according to Douglas E. Cowan, and included an article titled Is Romanism Christianity? in which T. W. Medhurst, a student of the famous preacher Charles Spurgeon, called Romanism a "Satanic delusion."
The term was frequently used in late-nineteenth and early-twentieth century Republican invectives against the Democrats, as part of the slogan "Rum, Romanism, and Rebellion" (referencing the Democratic Party's constituency of Southerners and anti-Temperance, frequently Catholic, working-class immigrants).[citation needed] A book titled The Three Keys to Hell; or, Rum, Romanism and Ruin was published in 1915. The term and slogan gained particular prominence in the 1884 presidential campaign[citation needed] and again in 1928, in which the Democratic candidate was the outspokenly anti-Prohibition Catholic Governor of New York Al Smith.[citation needed]
In Northern Ireland, the term was also used by Democratic Unionist Party founder Ian Paisley in anti-Catholic speeches.[better source needed]