In 1955 a Jewish sociologist named Will Herberg published a book that caused a stir in religious circles. The book’s title was Protestant, Catholic, Jew, and its premise was that by the time of the postwar religious boom then going strong in America, the country had become religiously tripartite.

Most people probably took this as welcome affirmation from social science of the toleration and mutual acceptance accompanying religious pluralism that by then were well along in becoming established parts of American life.

That, however, was a simplistic reading of Herberg. His further point, one he by no means welcomed himself, was that Protestantism, Catholicism and Judaism in the U.S. had been reduced to expressions of basically the same “great overarching commitment” — a commitment to the American way of life. Now, he added, all three were at risk of losing their distinctive religious identities in the great American melting pot.

I thought of Herberg and his book when I heard of the passing of Billy Graham, the famed American evangelist who died last month at the age of 99. Graham was a sincere believer and by all accounts an eminently decent man. His personal commitment to Christ and Christianity was transparently evident and highly edifying. Undoubtedly he did a great deal of good.

But along with all the pluses, Graham also was a de facto embodiment of the broad-based, non-dogmatic, undifferentiated version of religion that Herberg, who wrote as Graham’s star was on the rise, had in view in warning of the growing assimilation of Protestants, Catholics and Jews into American secular culture in a process that involved a thinning out of religious identity.

Mainline Protestants had of course been first to travel that particular road, even as evangelicals and fundamentalists were retreating into largely self-imposed cultural isolation following the disaster of the Scopes “Monkey Trial” in 1925. But by the mid-1950s the Catholics, Jews, and, increasingly, popular evangelicals such as Graham were catching up with the mainline Protestants while, as Herberg put it, “losing their capacity to resist dissolution in the culture.”

Much has changed in the world of American religion since then. The religious boom has long since faded. Other religious bodies, notably including Muslims, have become a presence on the American religious scene. And the number of religiously non-affiliated Americans has risen dramatically.

But one thing hasn’t changed. The constant is ongoing cultural assimilation, and the accompanying loss of religious identity, that was and today continues to be a central part of the American religious experience, described by Herberg as “essentially the ‘Americanization’ of religion in America, and therefore also its thorough-going secularization.”

To make his point, Herberg quoted a remark attributed to President Dwight Eisenhower: “Our government makes no sense unless it is founded in a deeply felt religious faith, and I don’t care what it is.” To which Herberg added: “And why didn’t he care what it was? Because, in his view, as in the view of all normal Americans, they ‘all say the same thing.’”

Much was said in praise of Graham after his death, and much that was said was well deserved. But along with praising Graham the individual Christian, one must also express reservations concerning the limitations of the version of culturally assimilated religion he stood for.

Protestants, Catholics and Jews haven’t yet worked out a viable response to the challenge of cultural assimilation in secular America. And Billy Graham, for all his decency and personal commitment, was not much help in doing that.

Shaw is a freelance writer from Washington and author of American Church: The Remarkable Rise, Meteoric Fall, and Uncertain Future of Catholicism in America.