In the case of the Peace Cross in Bladensburg, Md., the ostensible issue for the Supreme Court is whether the Constitution permits a local government to maintain a 40-foot World War I memorial in the shape of the Latin cross on public property, or whether this violates the First Amendment clause prohibiting the establishment of an official religion.

The deeper question is the long-term status of publicly supported religious symbolism — everything from the Peace Cross to “In God We Trust” on coins — in a nation that is rapidly becoming less and less religious.

And on that point, there may be nothing the court can do to stop or even slow the trend.

Across the industrialized world, people are losing interest in traditional religion. This process is most advanced in Europe; nearly 80 percent of Swedes described themselves as “not a religious person” or “a convinced atheist” in a WIN-Gallup International survey. However, the United States is catching up, or so most Americans suspect: Seventy-six percent told Gallup last year that religion is “losing influence” in this country. Twelve percent of Americans told Gallup they do not believe in God in 2017; only 1 percent dared admit that in 1944. And the proportion of those who “never” attend services — 28 percent in 2018 — has doubled in the past quarter-century.

Broadly speaking, that is a manifestation of capitalism’s destabilizing impact on tradition. Social scientists have long identified secularization as a consequence of economic modernization, but no one has done so more persuasively than political scientist Ronald F. Inglehart, professor emeritus of the University of Michigan, who has, over decades, assembled a vast quantity of international survey data to support that proposition.

A decline in traditional faith reflects the broader “cultural evolution” that accompanies generations of growing prosperity and technological advancement, Inglehart argues.

As poverty recedes and survival becomes less uncertain, people simply have more time and inclination to think for themselves about life’s big questions. Spirituality does not die out but rather takes “individually flexible forms,” as Inglehart puts it. Inhabitants of advanced industrial societies “tend to become less obedient to traditional religious leaders and institutions, and less inclined to engage in religious activities,” Inglehart writes in his 2018 book, “Cultural Evolution.”

Many commentators have noted the incoherence of the Supreme Court’s establishment clause doctrine. In oral arguments on the Bladensburg Peace Cross case Feb. 27, Justice Neil M. Gorsuch called the doctrine “a dog’s breakfast.”

A more charitable view would be that the court has been struggling to accommodate rising secularization (and diversity) within a constitutional framework written by men who could never have anticipated a case such as this one, in which three self-described humanists have been granted standing in federal court to complain, essentially, that a cross in a public park offends them.

Feeling bound to respect both the increasing numbers of such Americans who either aren’t Christian or don’t believe at all, and the shrinking majority that still is and does, the court has tried to conjure distinctions between forms of public support for faith that excessively “entangle” the state in religion or “endorse” it, and those that do not.

The court has yet to come up with answers that apply to all the possible thorny questions, and it’s unlikely that its holding in the Peace Cross case will prove any more satisfactory.

The simple fact is that the establishment clause is a powerful weapon in the hands of those who would eliminate all official support for religion and banish it from the public square entirely. Whatever its other merits, their position has the advantage of consistency.

It is also foreseeable that the power and popularity of secularist constitutional arguments will increase as cultural evolution accelerates.

As Inglehart notes, societies eventually reach a tipping point at which “conformist pressures” reverse polarity and begin to support changes they previously opposed. His example, and it’s a telling one, is the breathtaking shift in attitudes on same-sex marriage. Unthinkable for centuries, in the past decade it became not only thinkable but also normative and, consequently, legal in all 50 states. The Supreme Court’s 2015 decision in Obergefell v. Hodges merely ratified what the culture had already determined.

In some of the justices’ questions and remarks at oral argument last week, there was an implicit but unmistakable awareness that this exercise in constitutional adjudication is also about navigating a shifting cultural current.

Justice Stephen G. Breyer acknowledged that building a new Peace Cross today might be a problem, while voicing concern about a ruling that would authorize “people trying to tear down historical monuments” based on religious sensibilities.

There are any number of ways the justices could rationalize maintaining this giant symbol of a particular religion on public property; the cross’s relationship to a secular purpose, memorializing American war dead, is probably the most persuasive. It’s doubtful, though, that such a precedent, once established, would endure forever. Nothing does.

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