A Pew Research study, “The Future of World Religions: Population Growth Projections, 2010-2050,” makes interesting predictions about how religion will change.

Part 1 discussed some of the key conclusions:

• Christianity will be largely African by 2050. By that time, Africa will have more than twice as many Christians as North America, the second-most-Christian continent.
• Christianity’s days as the world’s most popular religion are numbered. By 2050, Islam will have almost caught up.
• While “Unaffiliated,” the category that contains atheists, will drop slightly worldwide during this period because of the greater baby-making capability of Christians and Muslims, the story in the U.S. will be quite different. By 2050, Christianity will drop (78% of the population to 66%) and Unaffiliated will be the big winner, with an increase from 16% to 26%.

Could upcoming changes in America predict how the whole world will go?

Notice where these worldwide demographic changes are coming from: more babies. Islam will soon surpass Christianity not because Islam explains reality better or because Allah is the one true god, but for no more profound reason than that Muslims are making more babies. (Which is also largely how Christianity became #1.)

The fertility rate is now 3.1 children per woman for Muslims and 2.7 for Christians. One option for Christians nervous about these changes is to have more babies, which is what the Quiverfull Movement is all about.

But this baby arms race won’t last much longer. Worldwide fertility was 5.0 in 1950, it’s 2.5 now, and it will reach replacement level of 2.1 (the fertility rate of a stable population) by 2050 (source, p. 25).

Demographic changes in religion are now driven by fertility, but as that factor wanes, what will change? Religion will no longer win simply by cranking out a surplus of indoctrinated babies and will have to compete on an intellectual footing.

To see how this may play out, consider world population charts with a sharp upward bend beginning several centuries ago as clean water technology, sewers, vaccines, antibiotics, and modern medicine reduced infant mortality. Modernity slowly brought the birth rate down, but this happened unevenly through the world. The population in Europe and the United States is now shrinking, and about half of the world population lives in countries with negative population growth, but it is still growing dramatically in other parts of the world, most notably in central Africa. (Religion thrives where social conditions are poor, which is one reason why Christianity and Islam are spreading in central Africa and in Arab countries.)

The drop in fertility rates means that the developing world will follow the West. Might the same secularization now happening in the United States happen there as well? The developing world has adopted Western technologies, they are following Western drops in fertility, and perhaps the secular West—where “no religion” is a viable and growing option to Christianity—will also be their future.

Whether atheism (or simply None of the Above) will continue to make inroads in Christianity as it’s projected to do in America for the next few decades is unclear. What seems almost certain, though, is that the time of fertility-driven growth will be over.

(Instead of Christianity becoming merely irrelevant, I propose a soft landing for it.)

Limitations to predicting the future

Let me pause and note that the Pew Research study is careful to list caveats. The conclusions may be wrong if they’re based on flawed assumptions. For example, Pew doesn’t speculate on what social conditions might drive atheism, and Christianity’s future in China is hard to predict.

Father Longenecker (the author of the “Atheism is Dying Out” post to which I responded last time) adds his own speculations of events that would change the picture. Some make sense—a global war, natural disaster, or Christian revival in the West. And some are ridiculous—God uses magic to convert Muslims to Christianity or makes birth control pills stop working.

Let me add a few on the atheist side of the ledger. Suppose the Catholic Church figured out that preventing a conception isn’t the same thing as killing anything and lightened up on their antagonism against contraception. Or even allowed abortion. Christian denominations have been fine with abortion in decades past. If the rapid rise of the anti-abortion movement in the United States is possible, the reverse is conceivable as well.

Suppose Islam gets its Enlightenment. Christians can (and sometimes do) find support for regressive policies in the Bible that are out of touch with modern society. But if Christians can dismiss nutty stuff from their holy book, Muslims could, too.

Suppose the move to secularism increases. Maybe there’s a snowball effect waiting to happen, and once enough Unaffiliateds or atheists go public with their unbelief, others will follow their lead—first the doubters who attend church because they feel they must and then other believers who unexpectedly have a new option to consider.

What do we actually want to drive the world’s beliefs?

What’s glaringly missing from Longenecker’s analysis is the claim that Christianity will win out because it’s, y’know, true. He could argue that Christianity simply explains the world better.

Nope—he throws in the towel on the intellectual debate and doesn’t even acknowledge it. He’s simply rooting for Christians to have more babies. (I’m beginning to see the value in conservative Christians’ anti-same-sex-marriage redefinition of marriage to be all about making babies.)

Longenecker is like a General Mills executive fretting that Cheerios will lose its popularity in the breakfast cereal aisle. His claims that Catholicism explains life’s big questions are as well grounded as that Cheerios scenario does. Without an intellectual grounding, Catholicism falls in with Cheerios as a lifestyle feature.

Once this baby-driven phase of religious expansion ends in the next few decades so that the effects of intellectual migration are clearer, it will be interesting to see who wins. The early indication doesn’t support religion.

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(This is an update of a post that originally appeared 5/13/15.)

Image from gill_penney, CC license

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