Religion Unplugged believes in a diversity of well-reasoned and well-researched opinions. This piece reflects the views of the author and does not necessarily represent those of Religion Unplugged, its staff and contributors.

(OPINION) Two January headlines a week apart signal that the past generation’s “population explosion” worries have reversed.

Observers fretted as China announced its population began to shrink last year as its birth rate reached a record low. Japan’s Prime Minister Fumio Kishida warned parliament that a declining birth rate means the rapidly aging nation is “on the verge of whether we can continue to function as a society.”

Then last Saturday a New York Times op-ed asserted that unfair burdens on wives and mothers created a “birth strike” and “marriage strike” that are “killing South Korea.” The nation has posted the world’s lowest fertility rate the past three years and deaths now outnumber births.

Such realities provoked the ever-interesting Times columnist Ross Douthat to ask whether “the defining challenge of the 21st century” will be climate change decried by so many analysts or, instead, the globe’s accumulating “birth dearth,” also known as “baby bust” or “population implosion.”

The second trend could well undercut societies’ “dynamism and innovation” and pit “a swollen retired population” against the “overburdened young,” he warned, while listing geopolitical factors in the coming “age of demographic decadence.”

Attention newsroom managers: This is an apt time for media to consider U.S.-focused big-think pieces on how religious communities are shaping population trends and, vice versa, how those trends affect religion.

Pro-procreation government programs appear to have limited impact in boosting birth rates, which instead reflect cultural values regarding marriage and children and complex individual decision-making. Articles might examine related abortion policy.

Traditionally, all religions cherish children and favor reproduction, notably in the case of the Catholic Church, as The Guy discussed here a year ago — (though today there’s little difference in fertility between U.S. Catholics and Protestants. On the other side of that equation, there’s universal acknowledgment that married couples raising children have been a pivotal constituency drawn to religious involvement.

GetReligion contributor Ryan Burge writes regularly on such factors. A recent Religion News Service article analyzed religion’s influence on decisions about whether to marry and whether to have children and how many. Also note this related Burge item from 2021 here at GetReligion.

If religion fosters child-bearing, and if the nonreligious have relatively few children, will U.S. faith communities grow in coming decades? Good question.

Consider the analysis last August from the pro-marriage Institute for Family Studies (media contact Emma Fuentes at emma@ifstudies.com and 434-263–9703). This report deserved more media attention and is a natural starting point for 2023 research.

The IFS drew data from the federal National Survey of Family Growth covering 1982 through 2019 and four rounds in 2022 to 2022 of scholars’ Demographic Intelligence Family Survey. IFS segmented out Americans on the basis of worship attendance, the devout who attend weekly, the mild religionists who attend less often and the nonreligious.

Importantly, future projections necessarily assumed no immigration will occur, since those numbers are unknowable, though obviously that’s not going to be the case.

Here’s the nub. Americans’ overall fertility is sliding below what’s needed for population replacement, though higher than in many other developed nations. There’s no prospect that numbers will bounce back.

Religion-beat professions should note: A little-noticed aspect is the “unprecedented” gap that developed in recent years between the relatively high fertility of the devout population and the low fertility among the nonreligious.

IFS puts the gap this way. Devout Americans’ birth rates are similar to those in India, Iran, Saudi Arabia, Peru or Mexico. Non-religious Americans’ reproduction is similar to the lows seen in Japan, Singapore, Greece or (despite its Catholic heritage) Italy.

That may cause churches and synagogues to hope this will stem their declining numbers. But “rates of conversion into irreligion are too high, and fertility rates too low, to yield stable religious populations” for U.S. religion as a whole, this report concludes.

The IFS finds that since 2002 the share of U.S. women of reproductive age who attend weekly has slipped from about 35% to 24%, or a mere 18% in the recent DIFS data. Among nonreligious women in a similar time frame, fertility has fallen 26%, but they are an increasing population now constituting 30% of women of reproductive age.

IFS also documented significant differences among religious groups. Its demographic projections for the coming generation — again, assuming no immigration — are that U.S. religion overall faces “stark decline.” Catholicism can expect a 40% decline, and liberal Protestant denominations face a 48% decline.

Yet these faith groups should grow: conservative Protestants in general, Pentecostalists and especially the nondenominational independent congregations whose numbers may more than double over the coming generation. Also Judaism will grow somewhat, but only because of birth rates among Orthodox Jews, while the more liberal, mainline flocks decline.

How might declining religious groups turn things around?

Simple. Their married couples on average have one more child, the U.S. fosters immigration and they then attract immigrant worshippers and they achieve the retention and conversion rates that certain Bible-believing Protestants show are possible in modern America.

Richard Ostling is a former religion reporter for The Associated Press and a former correspondent for TIME Magazine. He’s also worked in broadcast TV and radio journalism covering religion and received a lifetime achievement award from Religion News Association. This piece first appeared at GetReligion.org.