Religion by the numbers: Demography drives change

Demography drives religious change. That bald comment is too obvious to be worth making, but it’s surprising how little attention demographic factors receive in most histories of religion, particularly of Christianity. That neglect means we miss a very large part of the story.

Given a sufficiently high birth rate, a minority religious community can rapidly be come a dominant majority, with all that implies for distributing social power and shaping conflict. Alterna tively, migration can transform the religious economy of a hitherto static society.

Demographics also shape the prevailing forms of religion. A country with a marked youth bulge—with lots of adolescents and young adults—is far more open to explosive revivalism than a more sedate and middle-aged society. Changing demographics can also have a pastoral impact, revolutionizing perceptions of childhood and old age. Numbers may not be everything, but they certainly are something.

Also in the category of “what everyone knows” is the fact that Christian numbers are growing in Africa and elsewhere while they are stable or shrinking in Europe. What we miss in such a simple statement is the sheer scale of the demographic change, quite apart from any religious concerns. The global shift in populations represents one of the most significant facts of our time. And unlike religious changes, which are subject to so many qualifications about what we can and cannot know, the demographic story rests on quite solid quantitative foundations.

Take the continent of Africa. In 1900, Africa had around 100 million people, or 6 percent of the global population. In 2005, the number of Africans reached 1 billion, or 15 percent of humanity. By 2050, Africa’s population will be between 2 billion and 2.25 billion, which will then be about a quarter of the world’s people. Those numbers do not count African migrants in Europe and North America.

Population growth comes into even sharper focus when seen in a local context. By contemporary standards, just a century ago, human beings were sparsely distributed across large stretches of Africa. In 1900, the parts of East Africa that would become Kenya, Uganda and Tanzania were occupied by just 7 or 8 million people, in an area not much smaller than Western Europe. By 2000, the three countries had a combined population of 90 million. By 2050, they might have 260 million. Growth in West Africa was almost as staggering. In 1900, the lands that would become Nigeria had around 16 million people, rising to 160 million today and probably to around 300 million by 2050.

Now let’s set those numbers alongside those for Europe. In 1900 there were 400 million Europeans, a number that rose to 730 million today. But in relative terms, as a share of global population, Europe was in steep decline. Europeans made up a quarter of humanity in 1900, as against 11 percent today, and it is projected to fall to 8 percent by 2050. In 1900, Europeans outnumbered Africans by four to one. By 2050, Africans should have a three to one advantage over Europeans.

That global revolution echoes through every aspect of life, through all social and economic structures. For one thing, all those new Africans have to find somewhere to live, so Africa in coming decades will be experiencing the greatest wave of urbanization in human history. This fact has incalculable consequences for political stability and quite possibly for international tensions. Moreover, different parts of the world are marked by radically different proportions of young and old. Of the ten nations with the highest population growth rates, all but one are in Africa. All the nations experiencing population decline are in Europe, with the exception of Japan.

These numbers have major religious consequences, and not just for Christianity. In coming decades, the non-Arab share of Islam will continue to grow, with a far larger proportion of Muslims coming from Africa and particularly from south of the Sahara. But the change will have a much greater impact on Christian populations. As recently as 1900, Europe accounted for over two-thirds of the “Christian world,” with North America a distant second and Africa barely on the map. By 2050, by far the largest share of the world’s Christians will be found in Africa, which should have a billion or more believers. By that time about a third of the world’s Christians will be African, and those African Christians will outnumber Europe’s by more than two to one. The Christian world will have turned upside down.

We can argue at length over what those figures mean and what future forms of faith might look like, but the raw numbers are not going away.