The demographic future of the world

29 Mar 2024

An extensive new report on global fertility from the Lancet generated some headlines this week. Although its projections are a long way off—a generation to get to 2050, three to 2100—the effects of the trends will be impact the church over the years and decades between now and then.

The report says, quite simply, that global fertility in nearly every country has been falling since 1950, and will likely continue to do so. In 1950, the global total fertility rate (TFR) stood at 4.84; by 2021, it had fallen to 2.23. The total number of yearly births peaked in 2016 at 142 million and has been declining ever since. The ‘annual replacement rate’ is generally thought to be 2.1; today, 94 countries are above that rate, 44 of these in Africa. Of the 47 countries that had dropped below 2.1 between 1950 and 2021, only three rebounded above replacement levels—which bodes ill for any country that drops below.

The Lancet study foresees the global TFR continuing to decline, dropping to 1.83 in 2050 and 1.59 in 2100. It thinks only 49 countries will be of 2.1 in 2050 and only 6 above in 2100. If it’s difficult to rebound above 2.1, then this would seem to bode ill for the future. That’s obviously a very long range projection, and a lot can happen between now and then. But what’s clear is that fertility is declining globally while lifespans are increasing, which leads to aging populations and declining workforces, and resulting economic stresses.

What sorts of questions should we ask about how this projection will affect church growth?

1) Will it affect strategies for church planting? Slowing/crashing growth rates could mean less worry about getting ahead of runaway population growth. OTOH the Gospel is still spreading too slowly in unreached areas, so I’m still in favor of movements that get to people before they die—but crashing population growth rates means this is less of a factor in strategies.

2) What about the birth rate within the church vs. the birth rate in the country? Church growth is made up of both demographic (births minus deaths) and conversions (conversions minus defections). Crashing fertility rates means the church can’t count as much on population growth as part of church growth. There will be several nuances to this. A church that is more fertile than the surrounding population (often happens especially where agnostics and atheists are high percentages) will increase its share of the population, even with low birth rates. In some places, the church’s population growth may decline, but more slowly than the surrounding population (true in Eastern Europe), and thus also see a rise in % Christian. However, If a church’s demographic growth rate matches that of the wider population and it is suffering defections (nones, for example) with few offsetting conversions, then it could very well see mass decline.

3) How will fertility declines impact governmental policies, and even foreign policy actions? Some countries will see significant drops in their population. China, for instance, could decline to somewhere between 500 million and 700 million people by 2100, implying massive changes in political, economic power and missional strategy. So far, attempts to reverse the decline in fertility have not been fruitful. In between now and the other side of that drop, as a country’s leadership stares in the maw of demographic, economic, military decline, some governments may undertake rather drastic measures.

4) How will changing mixes of male/female distributions affect the church? Falling fertility rates can lead to falls in the number of women (some nations prefer boys over girls). Using UN Population Prospects 2022, I discovered that, in 1950, just 4 countries had over a million more men than women (making for all sorts of social dynamics): China, Bangladesh, India and Pakistan. By 2025, there were 10: China, India, Pakistan (but not Bangladesh), as well as Egypt, Nigeria, Indonesia, Philippines, Qatar, Saudi Arabia, and the UAE. Although the data doesn’t specify, I hypothesize a substantial part of the difference is the presence of large migrant populations that skew male. By 2100, the (very long term) projections suggest it will drop once again to 6: China, India, Philippines, Vietnam, Saudi Arabia, and the UAE. This has significant implications since (a) the church tends to skew female and (b) some denominations have theological beliefs about who can be a church leader (e.g. must be male, married, with children).

5) How will aging affect church and mission strategies? in many countries, ministries will need to shift away from a focus on children (not entirely, for there will still be children) and toward middle-aged and elderly populations (which will be increasing).

… there will be a significant increase in ‘older age’ life situations, diseases, etc. Cancers (mentioned in this week’s Data section), for example, are often correlated to older age. Other time-of-life situations (poverty, loneliness, mental diseases, etc) will also be faced. An article this week (plunging births push Japanese diaper maker to switch to adult market) illustrates this in the secular world. Articles from previous Roundups focused on ministry to the elderly illustrate this idea in the ministry sense.

… There are many cases where ‘if you get the children, the parents will come to’ will be expressed. As the number of children rapidly declines, there will be pressure on this ministry strategy. Also, in the past, I have heard several anecdotal stories of how the conversion of younger members of the family (e.g. grandsons) alienated the older members of the family (e.g. grandparents, who perhaps weren’t English speakers). We must think more about what it means to evangelize and disciple older members of a society.

6) How will falling birth rates affect economic opportunities - and in turn affect immigration strategies? in some people groups and countries, we may find that the ‘younger’ members of a particular group are often found in diaspora work in other countries, whereas the ‘older’ and ‘very young’ members of a particular group (e.g. grandparents, very young grandchildren) are still in the ‘home’ country. Thus, different approaches for different generations will be necessary to consider.

7) In addition, the migration that happens will introduce a large number of social and cultural pressures—who is welcome where, and what jobs they can do. Church ministries working with, for example, immigrants, may find themselves somewhat at odds with the wider culture.

The fertility study might almost be read as “we will eventually cease to exist because there will be no babies to replace us.” I personally don’t think it will go that far. The twists over roughly 75 years are impossible to foresee. But what is clear is that over the next generation, some of the ministry strategies taken “rather for granted” will likely not be as fruitful, and strategists ought to begin contemplate alternate possibilities now.

A version of this article appeared earlier as a commentary in my Premium Roundup. You should subscribe.