Roman Catholicism was a miniscule minority at the time of the establishment of the Thirteen Colonies, as many colonists had, of course, fled Roman Catholic persecution in Europe in the first place. Today, as the third largest Roman Catholic population in the world after Brazil and Mexico, it is the single largest profession of faith today in North America. Approximately 24.5% of Americans identified themselves as Roman Catholic, or roughly 1/3 of American Christians.
The National Council of Churches reports 67.5 million registered members of the Roman Catholic Church, with the next largest Christian denomination being Southern Baptist at 16.3 million registered members. There is a rough correlation between the growth of anti–Semitism in American and the growth of Roman Catholicism in America (primarily in the 19th and early 20th centuries), with Roman Catholic venues historically relatively the most consistently toxic–laden of the Christian denominations towards the Jews. As in Europe, the orientation of the constituents is heavily impacted by the tone set by the local bishop.
A study investigating the correlation between the unexpected dramatic rise of anti–Semitism in the young nation and the parallel growing percentage of the population which was Roman Catholic, might be useful towards getting at the root of anti–Semitism in America..
Sidestepping the contentious issue, as the ADL seems want to do, will not impress future chroniclers either. Perhaps the free pass extended to the (most certainly quite powerful) Catholic Church in America has expired…