A reason to drag yourself to church

He certainly did not see Catholicism as an ideal expression of religious observance. But virulently anti-Catholic seems strong. Add that what he saw as Catholicism is not what we see today. Nor was Adam's in any way a precursor to the nativism and bigotry represented by the KKK where Catholics were concerned.

Adams also was looking at a religion that was closely similar to the aristocratic and monarchical government that were rejected in the formation of both the Articles of Confederation and The Constitution. Considering that the Papal States effectively made Catholicism a supra nation-state, that made Catholicism automatically suspect to a newly formed nation where aristocracy was seen as at best a problem, if not an evil in political structures. By supra nation-state I'm referring to the nation-state of The Papal States, where the Pope was nominally the king, cardinals were (and still are) called Princes of the Church, and where there were archbishops, bishops, mongesniors, priests, etc., all seemingly parallel in monarchical and aristocratic organization.

Given that the idea of a nation composed of individual states, all of which were nominally democratic, without even symbolic heads of state (i.e., kings, etc.), I can see how Adams might have perceived Catholicism (or any other medieval structured religion) as potentially a weakness in maintaining democratic-republican governance.

While this resembles the anti-Catholic bigotry that existed in the KKK, and was heard in the anti-immigrant bigotry during the tremendous European immigrations to the US, I don't believe that they are the same. In the late 1800s, especially after the Civil War, the US had over a 100 years of developing traditions of democratic-republican structure (very imperfectly of course). Another aspect of that anti-Catholic bigotry is that Rome was on record as "anti-American." In a late 19th century published catechism, with the nihil obstat and imprimatur, the authors, "Americanism" is condemned. If i remember correctly the condemnation was based on the extreme materialism of American culture even at that time.

So I disagree with the description of John Adams as virulently anti-Catholic.