The image of the pre-conciliar Catholic Church in the United States as catechetically effective and politically potent can be hard to square with the long-term damage done to Catholicism's role in American public life by that very pre-Vatican II Catholic, John F. Kennedy.

Some biographers suggest that JFK became more religiously serious after his infant son Patrick's death in 1963. I certainly hope that was the case. For most of his life, however, Catholicism for John Fitzgerald Kennedy seems to have been less a matter of deep personal conversion than an ethnic marker -- sometimes useful, sometimes troublesome, but always irradicable. Kennedy regularly performed what were then known as his "religious duties." But their impact on his manner of life appears to have been minimal, and he had no grasp of Catholic political theory.

Speaking on Church-and-state to the Greater Houston Ministerial Association during the 1960 presidential campaign, Kennedy did American Catholicism a service by masterfully arraigning those who continued to indulge in that venerable American pastime, anti-Catholic bigotry: prejudices rooted in an ignorance that was amply displayed by the Protestant ministers who challenged JFK during the Houston meeting's Q&A session. But Kennedy put the bigots in the dock by getting as much distance as possible between himself and serious Catholic thinking on school choice and religious conviction's role in the public square, while seeming to acknowledge the possibility of a pope trying to boss around a Catholic president -- which was about as likely in 1960 as the Vatican launching a manned mission to the moon.

(The "Catholic issue" of that election cycle did produce one great line. Before the 1960 primaries, Harry Truman didn't evince much confidence in Jack Kennedy, whom he dismissed as "the boy." But Truman, who occasionally showed residues of anti-Catholic sentiment, also admitted that "It's not the Pope I'm afraid of, it's the pop" -- meaning Joseph P. Kennedy, whose enthusiasm for Joe McCarthy, coupled with his dismal record as the appeasement-minded U.S. ambassador the Great Britain during the early days of World War II, stuck in Truman's craw.)

John F. Kennedy, it is typically said, made Catholics "acceptable" as players at the highest levels of American politics. And, yes, his intelligence, wit, and grace confounded the image of U.S. Catholics as something less than the A-team, socially and culturally. But the price of acceptability was high. For the Houston speech and Kennedy's electoral success set the stage for several generations of Catholic politicians to treat Catholic teaching on the life issues as sectarian oddities rather than as what they are: convictions based on rational grounds accessible to all. That ongoing misrepresentation, which also involves a surrender to the very un-Catholic idea of freedom as mere willfulness, now touches other matters, including the legal definition of marriage and the agenda being pressed, against all scientific evidence, by the "Trans" movement.

I've thought of the Kennedy Effect a lot since Joe Biden became the presumptive Democratic presidential nominee in early spring. Mr. Biden's testimony to the power of his Catholic faith in helping him bear personal tragedy is, I believe, heartfelt; one can't imagine cool, rational JFK speaking in those terms about how he dealt with sorrow. Is Joe Biden's Catholicism really that much different than JFK's, though?

Aspects of Mr. Biden's Catholic self-presentation put me in mind of some of the folkways of pre-Vatican II tribal Catholicism. He sometimes treats the rosary as a charm or talisman -- famously wrapped around his fingers in the White House Situation Room while the SEAL raid on Osama bin Laden's Pakistani compound (which Biden opposed) was underway. "The nuns" Biden cites are campaign props, not unlike the religious sisters in JFK's joshing answer to a reporter's question about inflated numbers at his 1960 rallies: "Plucky [press secretary Pierre Salinger] counts the nuns and then multiplies them by 100." Jack Kennedy dealt with Cardinals Cushing and Spellman as power-brokers; Joe Biden seems to regard high-ranking clergy the same way, not as men with whom he might seriously discuss the moral dimension of public policy -- perhaps even to the point of being challenged by them. As for Vatican II, well: Mr. Biden's positions on contraception, abortion, and the nature of marriage reflect a sad ignorance of, or indifference to, the Council's Pastoral Constitution on the Church in the Modern World.

Joe Biden is no Traditional Latin Mass guy, to be sure. In other respects -- not least his repeated threat to shove his rosary beads down critics' throats -- his Catholicism is reminiscent of "The Last Hurrah": which is to say, something quite pre-Vatican II.

- George Weigel is Distinguished Senior Fellow of the Ethics and Public Policy Center in Washington, D.C.