A new report by Pew Research Center shows that in the next 35 years, the number of Christians and Muslims in the world will nearly be equal, as high growth rates in countries with significant Muslim populations, particularly in sub-Saharan Africa, outpaces that of Christian nations in the West.
The report says that religions with many adherents in developing countries – where the population is young, birth rates are high, and infant mortality is falling – are likely to grow quickly.
Much of the worldwide growth of Islam and Christianity is expected to take place in sub-Saharan Africa.
The region will experience the fastest overall growth, rising from 12% of the world’s population in 2010 to about 20% in 2050.
Today’s religiously unaffiliated population, by contrast, is heavily concentrated in places with low fertility and aging populations, such as Europe, North America, China and Japan.
As a result, by 2050 there will be near parity between Muslims (2.8 billion, or 30% of the population) and Christians (2.9 billion, or 31%), possibly for the first time in history. Globally, Muslims are the only religious group projected to increase faster than the world’s population as a whole.
Christianity began about six centuries before Islam, a head start that helps explain why some scholars believe that, in the past, Christians always have been more numerous than Muslims around the world.
But some other experts, including Oxford University demographer David Coleman and Columbia University historian Richard W. Bulliet, say it is possible that Muslims may have outnumbered Christians globally sometime between 1000 and 1600 C.E., as Muslim populations expanded and Christian populations were decimated by the Black Death in Europe.
Nigeria’s Muslim majority
By 2050, Nigeria is expected to have a Muslim majority. But Nigeria also will continue to have a very large Christian population. Indeed, Nigeria is projected to have the third-largest Christian population in the world by 2050, after the United States and Brazil.
In addition to fertility rates and age distributions, religious switching is likely to play a role in the growth of religious groups. But conversion patterns are complex and varied. In some countries, it is fairly common for adults to leave their childhood religion and switch to another faith. In others, changes in religious identity are rare, legally cumbersome or even illegal.
Over the coming decades, Christians are expected to experience the largest net losses from switching. Globally, about 40 million people are projected to switch into Christianity, while 106 million are projected to leave, with most joining the ranks of the religiously unaffiliated.
Modest net gains through switching also are expected for Muslims (3 million), adherents of folk religions (3 million) and members of other religions (2 million).
Some social theorists have suggested that as countries develop economically, more of their inhabitants will move away from religious affiliation.
While that has been the general experience in some parts of the world, notably Europe, it is not yet clear whether it is a universal pattern.
With Africa projected to post robust economic growth in the next few decades, more switching of Africans to the ranks of the unaffiliated could slow down the net increases in the number of Muslims and Christians in the world.
Why is it relatively easy for Christians to abandon the faith, compared to Muslims, for example? First, forsaking Islam is the crime of apostasy, punishable by death in some countries.
Memorably, there was the case of Meriam Ibrahim, a Sudanese woman who was sentenced to death in 2014 for apostasy. She was eventually allowed to leave Sudan and moved with her family to the US; a number of other Sudanese nationals have been convicted of apostasy in recent years, but they all escaped execution by recanting their faith.
But there could be other forces at play – perhaps Christianity is not “forceful” enough.
Catholicism “too cheap”
Writing in The Price of Everything, economist Eduardo Porter suggests that the Catholic Church, for example, has been losing adherents not because people stopped believing in God but because membership became “too cheap” compared with evangelical Christianity, which demands a bigger investment in its churches from members and thus inspires more loyalty.
It could already be playing out in Africa, and partly explains the rise of radical groups like Boko Haram, al-Shabaab and the Islamic State.
The fastest-growing versions of Christianity in Africa are the evangelical-pentecostal denominations with their emphasis on the “prosperity gospel” and “claiming your miracle”, but they are often criticised by the traditional, mainstream churches as being too driven by money.
By contrast, the radical Islam presented by a group like IS, for example, is distinctly millennial or apocalyptic, in which their jihad will remake the world as we know it, and usher in the last days.
Brutal as they are, IS, al-Shabaab and like-minded groups offer a higher purpose, an alternative to the greed, selfishness and excesses of capitalism (which the prosperity-gospel churches exemplify), and in the caliphate, something not just to die for, but to live for.
It partly explains the appeal of such groups to young, middle class people, who would abandon a comfortable life to join a group like IS or al-Shabaab.
Already, there are signs of it in Kenya. In the recent Garissa University massacre in which 148 people were killed by al-Shabaab gunmen, the group’s ringleader was a young law student with good grades, who had attended the University of Nairobi’s school of law and was at home in middle-class Nairobi.