John F. Kennedy's victory over Richard Nixon in 1960 came soaked in symbols and lessons. It was the triumph of vision over experience, rich over poor, East over West, the playboy over the prig. And because a Catholic, for the first time ever, defeated a Protestant, the outcome was said to mark the burial of religious bigotry. Kennedy provided the case study for candidates ever since who have faced some version of the Religion Test. But his was an advanced course in strategy, judgment and rhetoric, and it may be harder for future candidates to pass than they realize.
The first time America searched her political soul—when Al Smith ran for President in 1928—perhaps 16% of the country was Catholic. Critics warned that if he won, he would take his orders from Rome and make Catholicism the national religion. But by 1960, the Catholic population had more than doubled, to 42 million, and urban Catholics...