“Defending and extending the secular definition of the American state,” he has written, “became the (often unstated) core political priority of America’s organized Jewish community.” The emergence of the evangelical Christian “religious right” in the 1980s especially reinforced that belief.

The Catholic experience has had its share of nuance. Leslie C. Griffin, a professor of constitutional law at the University of Nevada, Las Vegas, spoke recently of the way earlier generations of Catholics teased apart good and bad types of church-state separation. Good meant denying formal state power to Protestants. Bad meant refusing governmental aid and accommodation to Catholic institutions, especially parochial schools.

And while the Jewish organizational sphere developed largely along secular lines — Hadassah, Anti-Defamation League, American Jewish Committee to cite just a few examples — American Catholics advocated largely through overtly religious bodies such as the United States Conference of Catholic Bishops.

Far from being predictably conservative, the bishops have taken liberal positions on issues such as nuclear arms, welfare overhaul and immigrant rights. Always, though, their positions have been put forth as the product of Catholic doctrine and social teaching, theology deemed a legitimate part of public debate.

“The Catholic Church has wanted separation in the sense we don’t want the king picking the bishops, but we also believed you could have cooperation in civil society,” said Richard W. Garnett, a professor of law at the University of Notre Dame. “Whereas in America, separation became a code for no money for Catholic schools or we don’t want religiously oriented morality shaping public policy.”

The divergent Jewish and Catholic sensibilities are measurable. In a 2007 survey by the Pew Forum on Religion and Public Life, 43 percent of Catholics agreed that “government should do more to protect morality”; just 22 percent of Jews concurred. The survey also found that Catholics were more than three times as likely as Jews (33 percent to 10 percent) to attend a religious service weekly. Catholics are also twice as likely as Jews (55 percent to 27 percent) to rate religion as the most important or a very important factor in their lives, according to a 2012 survey by the Public Religion Research Institute.

All of which helps one make historical sense of the two court decisions. Yes, the conservative bent of the court has as much to do with the number of vacancies that happened to come up during Republican presidencies. Yes, too, Catholic identity does not trump every other personal or legal consideration. Justice Kennedy, usually part of the court’s conservative wing, cast the decisive vote last year to overturn the Defense of Marriage Act, giving a major victory to the movement for same-sex marriage.