And it likely will, with the largest percentage of those losing their religion being young adults who are about as old as that REM reference: people around 30 and under.

It's a kind of "cultural whiplash" from religion to secularism that's hit the United States much faster than it has other parts of the world, said theology and sociology professor Stephen Bullivant.

Bullivant, a practicing Catholic who teaches at St. Mary's University in London and the University of Notre Dame in Sydney, spoke to Grid about why Americans are leaving Christianity in droves and the demographics that are seeing the (ahem) ungodliest declines. His new book, "Nonverts: The Making of Ex-Christian America," came out in the U.S. on Dec. 1.

Young adults are leading the mass exodus

Bullivant made it clear that it's important not to glom all young adult nonverts as having one big reason for leaving the church. "Each person has a complex story, and we need to recognize the personal journey," he told Grid. That said, he added, there are larger trends we can examine.

For example, the largest demographic of nonverts, younger adults, will raise their children as "nones" -- people from nonreligious families. And while a tiny percentage of nonverts return to religion, nones rarely embrace religion at any point in their lives.

Bullivant noted that it's not shocking that young adults are the ones leaving at the highest rates. "When people do nonvert," he said, "they tend to do in their early to mid-20s."

And to those who dismiss the trend as just young people trying something different who will eventually come back to the church, that is not what the data shows. Not only have the percentages of adults under 30 claiming to have no religion increased dramatically over the past 50 years, other age groups saw rises as well, Bullivant said.

The move toward secularism happened incredibly fast in the U.S.

While the trend toward atheism and agnosticism in Europe has been a slow but steady decline, Bullivant said, the increase in Christians dropping the faith didn't really take off in the U.S. until the early 2000s, and the decline since then has been steep and quick.

For people who study such trends, there was kind of this feeling in the '90s that if a rise in secularism hadn't happened yet in America, there was no reason to think it would. "Even the most dramatic historical examples of religious growth or decline tend to occur over many generations," said Bullivant. "But then it was as if in the early 2000s, something was released."

It wasn't so long ago, when you are talking about as big a culturally religious shift as we're talking about, he added.

And it's important to note, said Bullivant, that it wasn't about an influx of secular immigrants or nones raising throngs of nonreligious babies. It was about Americans deciding they were not tied to any religion. Interestingly, while a third of Americans that identify as nones say they are atheist or agnostic, Bullivant notes in his book, the rest have varying degrees of belief in God -- Christian or otherwise.

And the big question: Why now?

Bullivant said that if you look at the big picture of American 20th-century culture, you stop asking, "Why is it happening now?" and start asking, "Why didn't it happen earlier?" You can't just blame shifting political views.

"It's about looking at what happened in the 20th century that dampened down the possibility of being nonreligious -- and then what changed?" he asked.

Bullivant said there are three main answers to that question: the Cold War, 9/11 and the internet.

If you compare the Cold War in Europe to the Cold War in the U.S., there was one major difference when it comes to religion. In the U.S., it was very much about Christian America vs. godless communism, whereas in Europe there just wasn't that religious element.

In Europe, it was OK to explore secularism a bit, he said, whereas in America questioning their faith or going so far as to proclaim they were atheist or agnostic was really not socially acceptable on a political, cultural or religious level.

It's also about who the atheist and agnostic influencers were in both parts of the world. In the U.K., for example, it was respectable establishment intellectual figures -- such as the mathematician and philosopher Bertrand Russell. In the United States, said Bullivant, you had people like Madalyn Murray O'Hair, who "while fascinating for all sorts of reasons was very easy to depict as someone who had been a communist, who had tried to defect to Moscow and was a divorcee" which all made her sort of a social outcast during a religiously overtoned Cold War.

The generation born after the height of the Cold War -- in the early to mid '80s -- didn't grow up with propaganda and blacklist fears, said Bullivant, so there is a safe space for the idea of a nonreligious life to open up.

When 9/11 happened, Bullivant said, then you have the new atheism with many prominent people coming out and publicly questioning faith in a higher being -- such as Christopher Hitchens, Sam Harris and Richard Dawkins -- and it becomes OK to reevaluate what you believe, said Bullivant: "They opened up a nonreligious space."

And of course the internet, Bullivant added. That was happening at about the same time, and it gave people access to communities of people also questioning their faith. Bullivant particularly saw this when interviewing ex-Mormons and ex-evangelicals.

"If you're raised in small-town Texas or Idaho and everyone you know is some kind of Christian, you're in a kind of bubble. And then with the internet, you start getting support groups online with thousands of members and that helps erode those bubbles," he said.

One thing Bullivant said is overemphasized when it comes to examining why people leave the church: shifting cultural values.

As people's opinions in the U.S. changed on women's roles in society, abortion and same-sex marriage, it was absolutely difficult for the churches to deal with, said Bullivant. They thought it meant "alienating large segments of people" who didn't agree with the church's stances on issues.

But, if you look at the Episcopal Church, which has changed along with the culture, its numbers are tanking, said Bullivant. Churches shifting with the times doesn't seem to "fill the pews."

"When Catholics say, 'The reason young people are leaving is because they disagree with the church on abortion and contraception,' they do disagree with the church, and abortion and contraception, and gay marriage and all sorts of stuff," he said. "But it's very unlikely that if the church changed those positions, or softened them in a pastoral way, that those people wouldn't leave or that they'd come back or anything like that."

The rise of secular, rather than religious, cult figures after covid

Interestingly, said Bullivant, historically cataclysmic events -- the Civil War, World War II -- often trigger religious revivals on the fringe of the mainstream, such as cults. The fact that that hasn't been apparent with covid, the most recent cataclysmic event, is more evidence of a waning religious mainstream, he said.

The closest recent group that's come is perhaps the rise of QAnon, he said, but that's more a secular than a religious movement.

"In the past, Q would be some kind of angel or Virgin Mary or Native American shaman or religious thinker. Q is meant to be more of a civil servant, functionary," he said, "and the argument is that, well, you need a strong religious center to have wild fringes popping up."

VOL: This is pure sociology and does not consider what God might do in revival for the post-Christian American church