In one profoundly, maybe transcendently important respect, America and Europe seem destined to become ever more unlike most of the world around them — even as non-Western nations continue to catch up economically and technologically.

Devout agnostics, beware. The world is becoming more religious — and probably more ardently and conservatively religious.

This trend, shaped by global tides in belief and unbelief measured in “The Future of World Religions,” a 2015 report from the Pew Research Center, is likely to be more pleasing to people of faith than to doubters. But then, many things are, it seems. In a brand-new survey this month, Pew reports that “highly religious Americans” are happier than the rest.

Four big belief groups account for nearly 9 in 10 of the world’s people — Christians, Muslims, the “unaffiliated” and Hindus. Between now and 2050, Pew scholars project, each of these groups will grow along with global population — but only one will grow as a portion of the total.

That would be Muslims, who will expand from about 23 percent of world population in 2010 to about 30 percent by 2050 (the growth represents almost 1.2 billion additional Muslims).

Meanwhile, only one of the big four groups will noticeably shrink as a portion of the world’s people in the decades ahead. That would be the unaffiliated — atheists, agnostics and those with no religious preference. Let’s call them the “unreligious.” Their proportion of world population will fall from about 16 percent today to about 13 percent in 2050, says Pew.

Curiously, though, and significantly, in the U.S. and Europe the unreligious population will surge in the next 30-odd years, right alongside swelling Muslim populations — surely adding to the West’s cultural complexities, not to say its cultural contradictions.

In Europe, Pew researchers say, Muslims will make up fully 10 percent of the population by 2050 (up from less than 6 percent today), while the unreligious will by then constitute 23 percent.

In the U.S., the unreligious will soar from about 16 percent of the population today to well more than one-quarter of all Americans in 2050.

Muslims will remain a small part of the U.S. population, Pew says, but their relative size will more than double, from 0.9 percent of the total to 2.1 percent by 2050.

In the process, Muslims will go from representing only half as large a portion of Americans as Jews do today to constituting a segment 50 percent larger than America’s Jewish population.

World Christianity, too, is being transformed. Projected to hold steady as a portion of the global population (which will require 750 million more believers by 2050), Christianity will continue increasingly to make its home in the Southern Hemisphere, and especially sub-Saharan Africa, where almost 40 percent of Christians will live in 2050. By then barely a quarter of world Christians will be found in Europe and North America combined.

This emerging new Christendom, rooted in the developing world, seems likely to be more passionate and traditionalist in tone, doctrine and social outlook than the modernizing Christianity of the contemporary West.

The challenges that loom in these intersecting trends are formidable. History’s epic encounter between Christianity and Islam doesn’t seem likely to get any simpler or less eventful. Yet the “clash of civilizations” that could shake this century may not come so much between faith traditions as between an empire of faith and an empire of skepticism.

For secularizing America and Europe, the imperative of understanding and effectively interacting with Islam — its complexities and varieties, beauties and internal conflicts and its vulnerability to radical interpretations — will only grow as that ancient desert faith advances demographically around the globe, including within the West’s societies, almost as dramatically as it once swept across the Mediterranean world and beyond.

Yet the waning role of religion in the West — especially among political and cultural elites — may make deep understanding increasingly difficult. The simple reality that religion can matter is, after all, one of the things unbelievers have a hard time believing.

Persons of faith who confess different creeds may fear or even hate one another — but they share certainties about the nature of life and what matters most. And shockingly to secular Americans, what matters most to many believers may not ultimately be life, or liberty, or the pursuit of “happiness.” It is helpful to have a worldview that at least comprehends less-worldly pursuits.

In his fine 2012 book, “Righteous Minds,” New York University psychologist Jonathan Haidt wrote of his cathartic discovery that he belongs to an exotic race of what he calls WEIRD humanity — Western, educated, industrial, rich and democratic. The bulk of our fellow humans around the world, he says, treasure values such as sanctity, authority and loyalty with a passion we WEIRDos seldom can fathom.

Religion is a big part of all that. Yet it’s been a sort of article of faith in the WEIRD world that the future belongs to science and skepticism and maybe lukewarm “spirituality.” In the long run, revelatory faith — or anyhow fundamentalist religion — is “on the wrong side of history.” Right?

The Pew study’s bracing suggestion that the irresistible force of demography may be pushing history down a different path is another thing some of us may have a hard time believing, or adjusting to.

D.J. Tice is at Doug.Tice@startribune.com.