Most professional researchers know better than to try to predict the future with any level of specificity. Countless theorists have already come and gone, offering astoundingly inaccurate predictions—and the more specific their theories, the more laughably their assertions inevitably erred. Moreover, predicting the future of a complex human phenomenon like religious faith is an even more speculative endeavor because faith is very, very complicated.
But that certainly hasn’t stopped anyone from trying.
In 2015, and again in 2017, the Pew Research Center analyzed population growth statistics of faiths from around the world to assess which birth trends, should they continue, would lead to a rise or fall in particular religious groups, extending into the year 2050. Their results were encouraging for nonbelievers and so-called nones of the National Census, whose upwardly trending numbers were predicted to keep on rising. But Pew’s predictions were even more encouraging for Muslims, whom they slated to become a much greater percentage of the world’s faithful in the decades to come.
The rising number of nonbelievers out there is game-changing. I am often told, however, that this rise means far less than I think because Muslims are simply out-reproducing every other group and will continue to do so. A birthrate differential is no trivial matter—young, impressionable minds have always been a crucial conduit for religious beliefs, keeping those beliefs believable. Children are overwhelmingly likely to grow into the beliefs of their parents, regardless of the faith in question (they can be just as easily socialized into nonbelief, as new research indicates).
However, most of us nonbelievers and religiously unaffiliated were not socialized this way. We had to disaffiliate from the faith of our upbringing and become nonbelievers, despite the many years of indoctrination we received. Hence, while religious socialization may certainly provide faith with a jump start on nonbelief, this is not a lifetime guarantee of victory.
In addition, researchers routinely underestimate the degree to which social development affects birthrates. Theorists often fail to acknowledge that fertility rates are in free-fall across much of the developed world and that more and more of the world is increasingly moving toward that level of development.
Economist Max Roser, now responsible for heading the excellent web publication Our World in Data, was once tasked by Bill Gates to provide readers with the three greatest trends of human civilizations up to the present day. Roser opted to point out that infant mortality and extreme poverty levels are the lowest they’ve ever been and that, since 1960, the world fertility rate has fallen by half. Roser concluded that, as women gain more access to improved educational and employment opportunities, they decide to put off having children for longer and ultimately have fewer children in total.
One reason these data points matter here is that the poorest nations on Earth tend to be the most religious. As these countries develop, their fertility rates increasingly come to resemble those of highly developed, postindustrial nations. Indeed, the areas now achieving the most significant relative gains in metrics like access to education for women, child mortality and material development are precisely those places previously predicted to be teeming with religiosity by 2050. In 2017, Pew predicted, for example, that sub-Saharan Africa would be the primary focal point for Christianity in 2050, in terms of numbers of believers. Gains in the societal metrics mentioned above throughout Africa, however, are hard to ignore. Will such gains lead to a greater than predicted drop in fertility among religious individuals there? Arguably, yes.
If a greater proportion of the world’s population is enjoying (or will come to enjoy) something resembling a postindustrial life, birthrates among almost all religious and cultural groups ought to plateau towards a mean average over time. Consider that, in September 2018, an estimated half of the world’s population (roughly 3.8 billion people) reached a level of economic prosperity deemed by Homi Kharas and Kristofer Hamel at the World Data Lab to be the equivalent of middle class or above. Kharas and Hamel estimate that one person leaves extreme poverty every second, while five people per second enter the middle classes: “for the first time since agriculture-based civilization began 10,000 years ago, the majority of humankind is no longer poor or vulnerable to falling into poverty.”
Of course, some criticize the goalposts used to assess poverty levels. Such criticisms, however, typically have more to do with how we are reaching these levels, why, and what constitutes extreme poverty. But, if relative well-being is increasing—even if more slowly than some economists think—it will likely impact fertility patterns as predictably as in the past.
Roughly half the world’s nations now have fertility rates below the replacement level cut-off of two children per couple. Across Europe, some fertility rates have slipped to below 1.5. Some researchers believe that countries like Germany and Italy could even see their population sizes literally halved in the next 60 years. In May 2018, the American Centers for Disease Control and Prevention (CDC) officially reported that the US birthrate had fallen to its lowest point in 30 years (summarized here).
More importantly, these trends are likely to have more dramatic effects in areas experiencing additional relative growth. In Iran, for example, where Muslims constitute roughly 97 percent of the national population, birth rates have consistently trended downward over time at a rate faster than that of the nations mentioned above. In 1985, the fertility rate was approximately 6.2 children per woman. By 2014, it had fallen to 1.7.
A drop so large over such a short span of time is statistically atypical, given how long this process took many Western nations. It took fertility rates 95 years to fall from 6 to 3 children per woman in the UK. In the US, the process took 82 years. In Iran, however, that transition took only ten years. In Bangladesh—which Pew estimated would be home to a nearly double-digit percentage of the world’s Muslim population in 2050—it has taken only 20 years for fertility rates to fall. In Tunisia, it took only 21 years for fertility rates to fall from 6 children per woman to 3.
Rapid increases in education and development could lead to levels of native population decline similar to those we see in the West—but on a global scale. One data set from the International Institute for Applied Systems Analysis predicts that the world population will increase to 9.2 billion by 2050, peak at 9.4 billion in around 2070 and then start to decline worldwide, falling to 9.0 billion by the end of the century. Those trends are not immediately intuitive, if you have been educated in the Malthusian nightmare scenario experts used to predict, using bar charts to illustrate the runaway, exponential population growth that would lead to our inevitable ruin. The concept of peak child has been floated to convey precisely this idea.
It is therefore far from clear that the future of faith will play out as previously predicted. Research indicates a powerful direct correlative between societal development and religious nonbelief. More and more people are leaving poverty to enter the middle classes worldwide—and if increasing development is correlative with a drop in conservative, supernatural religiosity, the thriving future of religious faith, in general—and the Muslim faith, in particular—is far from assured.
Naturally, I am tempted to take these two concepts (correlative development and religious nonbelief, development and fertility drops) and predict that an increasing share of the world’s population will become patently irreligious in future. But that veers dangerously close to a fairly specific prediction—and we know how unreliable such predictions can be. However, we should certainly take some of the current predictions with a healthy dose of salt.