Although I have never claimed to be very statistically oriented, one number in particular fascinates me as a way of understanding the world, and that is: 2.1.
Specifically, that is the crucial figure when looking at a society's fertility rate, the average number of children that a typical woman will bear over the span of her lifetime. If the rate is exactly 2.1, then we can expect that, other things being equal, the population of that society will remain roughly constant, neither growing nor shrinking. The population will in other words just replace itself.
A higher figure means a growing and younger population. Below 2.1 means an aging and contracting society.
That much is well known, and social scientists pay a great deal of attention to fertility rates when predicting trends like the number of active workers in the labor force, or the relative number of active taxpayers to dependent elderly. But increasingly, I have come to believe that this figure, 2.1, represents a critical measure of the degree and depth of religious adherence in a given society.
And if I am right about that, we can look to some quite startling religious trends in future decades. Any church wanting to imagine its future should have that 2.1 figure firmly branded on its collective consciousness.
What has faith got to do with fertility? To see the answer, we can usefully look at Europe, where fertility rates began to collapse from the late 1960s onwards, as part of the much discussed demographic transition. Rates reached lows unprecedented in human history: 1.39 currently in Italy, 1.41 in Germany, 1.47 in Spain, and even lower numbers in Eastern Europe (1.28 in Ukraine, 1.26 in the Czech Republic). Falling fertility has coincided so closely with massive secularization that we must at least ask whether the two phenomena are related, even if not in a neat one to one relationship.
But linkages are highly probable. Fertility is likely to fall when women move into the workplace and become independent social and political actors, who are reluctant to heed the church's strictures on their moral conduct, particularly in matters like divorce, contraception and abortion. Also, the reason why people have fewer children in the first place is often because they no longer feel subject to the demands of religion and family pushing them to reproduce as their ultimate goal in life. Society becomes atomistic and individualist rather than organic and traditional.
A society in which people regard relationships as intended chiefly for companionship and mutual satisfaction is also more open to unconventional sexual arrangements, and to innovations such as gay marriage. Finding themselves in constant disagreement with church stances on politics -- seeing the churches apparently on the wrong side in all the incessant culture wars -- people become disaffected from organized religion.
Moreover, the fact of having fewer children is itself a powerful secularizing force.
If a typical woman has six or seven children, that family is probably going to be closely tied to a complex network of religious institutions, to church and parish school, to shared rituals and celebrations like First Communion and confirmation classes. Take the children out of the picture, eliminate the need for mass socialization, and watch church attendance collapse, followed closely by vocations to the priesthood and clergy. And then watch a generation of youngsters brought up without even a nodding acquaintance with or respect for any form of organized faith. In other words, look at a pattern precisely like what has happened across Europe since the 1960s.
For the sake of argument, assume that the model I am offering here is correct, that low fertility correlates with secularization -- not that the one causes the other, but that the two proceed together in a closely intertwined way. Why does that matter outside Europe? As I have suggested elsewhere, the consequences are explosive, particularly for the Islamic world.
Since the 1980s, fertility rates in several Muslim countries have collapsed at rates even faster than Europe's. The change is most spectacularly marked in Iran, where a typical woman can expect to bear 1.88 children in her lifetime (down from over 6.0 in the mid-1980s). Almost as dramatic are the falls in North African countries such as Algeria, Morocco and Tunisia.
Coincidentally or not, the wave of social protest that we call the Arab Spring began in Tunisia, where sharply declining fertility illustrated the radical ongoing changes in gender and family structures, and individual expectations. I believe that these changes are the harbingers of a long-term secularization that within a few decades will make countries like Iran as cool to organized faith as Western Europe itself.
But before Christians cheer, they might pay serious attention to the demographics of regions they have come to consider as their greatest hopes for future growth. In terms of numbers, by far the greatest hopes for Christian growth can be found in Africa, where the demographic transition is still not even a rumor. Classic fertility rates persist in Uganda (6.69), Ethiopia (6.02) and the Congo (5.24), all centers of spectacular church growth in recent decades. Nothing short of a cosmic catastrophe can prevent Africans making up an ever larger share of the world's Christians -- over a third by 2050.
Scholars still tend to lump Africa, Asia and Latin America together under some overarching label such as the Global South or the Third World, and in some ways, that concept has merit. In demographic terms, though, it is dangerously outmoded. While Africa remains fixed in Third World fertility patterns, the great transition is already far advanced in other regions where Christians have until recently boasted their greatest achievements outside the traditional Euro-American world. This is especially true in the Pacific Rim, where fertility rates look distinctly European, or even East European. China's fertility rate is 1.8, South Korea's is 1.23, and Korean church leaders worry loudly about the secularization of their youth, even amidst all those mighty megachurches.
Trends in Latin America are also advanced, despite common US stereotypes about explosive Latin birth rates. Among the countries that officially boast some of the world's largest Christian populations, Brazil's fertility rate stands at just 2.18, and is projected to fall very sharply in coming years. So is Mexico's, currently at 2.29. Several Latin American nations are already well below replacement rate, and their populations are aging accordingly. Despite all the successes of rising churches in the region -- especially Brazil's Pentecostal and evangelical denominations - scholars are already warning of secularizing trends. In recent polls, a startling and growing number of younger Brazilians report having no religion whatever, a trend that bears watching very closely indeed.
I am well aware of the problems of taking fertility rates as a mechanistic way of predicting faith patterns: people just do not act in such slavishly neat ways. Particularly thorny is the issue of using fertility rates for an entire country, with all its local divisions and distinctions. When we read for instance that modern Turkey has a fertility rate of 2.03, what we mean is that the rate is far lower than that among city dwellers, particularly in the western parts of the country, and far higher in among rural and small-town dwellers the inland and mountainous regions of the nation's Qur'an Belt. Putting the different regions together creates a misleading average.
But the Turkish example is suggestive. Around the world, we will probably see similar distinctions of both fertility and faith, whether we are looking at Muslim regions of the Middle East, or Christian lands of Latin America. Instead of religion declining uniformly across countries, we can expect to see ever greater divisions, and conflicts, between the prosperous secular city dwellers and the more fervent and fundamentalist true believers in less wealthy and more remote regions.
Making the confrontations still more intriguing, we can expect that the people from the backwoods -- the fundamentalist hicks -- are going to grow steadily in relative and absolute numbers, by dint of their birth rates. The political implications are many, and frightening.
So while I do not claim to predict the future of the world, I do know a tool that is extremely useful in attempting that task. And the tool is called: 2.1.