Christian, Islam growth rates

28 Jul 2023

At a global level, Islam has a faster annual growth rate than Christianity.

a) For the past several years the annual Status of Global Mission (of which the most recent one is always linked on my Charts page) reports Islam has been growing globally at about 1.87% p.a., while Christianity is growing globally at a rate of 1.18% (the same as the global population). However, just because Islam has a faster growth rate, it doesn’t follow that it is or will be the biggest religion.


b) In the last iteration of my Global Christianity Report, I included a graph that showed Islam expanding to above 4.5 billion adherents (below). This estimate was based on the global annual growth rate of Islam. I’ve become increasingly of the opinion–especially with so many analyses coming out about the declines in population growth rates–that to project this all the way out to 2100 was to significantly over-estimate Islam’s prospects.


c) Islam gets headlines for its faster growth rate in certain mostly-Christian countries, but such growth rates can be ‘clickbaity’ and hide where real growth mostly occurs. Consider: a family of 2 that has 2 children has grown by 100%. A church of 1,000 that grows by 10% has added 100 people. Fast rates of growth in small populations only outstrip larger surrounding populations if the growth rates are maintained over time., and they rarely are. Globally, Christians are more numerous (2.6 billion) than Muslims (2.0 billion). Muslims are adding somewhat more people than Christians each year, but for Islam to globally have more people than Christianity, it has to sustain its growth from 2050 to 2100. Can it actually do that?

d) Islam has had a higher growth rate globally because it is strong in countries with traditionally high fertility rates. Islam’s rate is higher in 90-odd countries, while Christianity’s is higher in 137 (based on AGRs as given in the last edition of Operation World). Christianity has an edge in low-fertility countries, because it grows through both births and conversions; Islam, on the other hand, rarely grows by conversion, and so it is very sensitive to any drop in birth rates—and as readers of the Roundup know, birth rates all over the world are dropping.

e) To get to a better answer, in the past month, I went back to a country-by-country estimate of Islam over the decades (with future projections), and tied it to the latest UN Population Estimate (running through 2100). This analysis has led me to revise my estimate of Islam vs. Christianity in 2100 (and this will be in the newer version of the presentation). By this estimate, Islam and Christianity will be nearly tied at around 3.8 billion adherents. Islam’s steep upward climb will, I think, fall off with the falling birth rates. It’s still very possible Islam will have higher numbers in 2100—but I doubt it will be markedly higher.


Islam has the advantage in places where the birth rate is high, and some level of conflict or pressure leads to emigration of other religions. But in the places where it is strongest, the fertility rate is dropping drastically. And in the largest populations of the world, no shifts seem likely to make up the difference, as Islam gets no benefit from conversion:

  1. China – Christianity outstrips Islam, 2.7% to 0.3% AGR – and Christianity 10% (or more) vs Islam 2%. Both still small-ish minorities of the country.
  2. India – Christianity 3.7% vs Islam 2% AGR, but Christianity is 6% vs Islam’s 14% of the population. For the moment, Islam will be larger—although “under the radar” rapidly multiplying movements could change that. But both are still minorities of the country.
  3. USA – Islam faster (1.9% to 0.5%) but Islam is a tiny minority (1.6%). A growth rate of 1.9% will double the population in 37 years, from today’s roughly 5 million to ~2050’s 10 million. If the growth rate held (a big IF), Islam could reach 20 to 25 million by 2100.
  4. Indonesia – Christianity faster but small (16%). Islam likely to be the majority through 2050 and probably 2100, and therefore unlikely to make unforeseen gains.
  5. Pakistan – Christianity also faster but small here. Islam is also likely to be the majority here through 2050, and probably 2100, so unlikely to make any unforeseen gains.
  6. Brazil – Islam very fast, but also very tiny (less than 1% of the population). Christianity still the staunch majority, likely near 80% in 2100.
  7. Nigeria – Islam and Christianity are nearly tied, with similar sizes and growth rates. By 2100, it’s likely Christianity will have an edge. But through 2050, I expect the “tie” status to remain the same.
  8. Bangladesh – Christianity faster-but-very small; Islam remains the majority in a similar situation to Indonesia and Pakistan. More likely to have losses than gains.
  9. Russia – Islam fast-but-tiny, with various traditions of Christianity dominant. Note that evangelical Christianity is growing at 2.3% (but it’s a small portion).
  10. Mexico – nil growth for Islam; Christianity remains the majority.

f) As always: it is impossible to predict precisely and accurately what the religious makeup of the world will be like in 2050, let alone 2100. The best we can do is give our assumptions, methodology, and the results as a picture of a possible and even, perhaps, probable future. Here’s my current estimate:

In 2100, I guess/estimate/think the following 11 countries will each have more than 100 million Muslims: Pakistan, Nigeria, India, Indonesia, Egypt, Bangladesh, Niger, Afghanistan, Iraq, Ethiopia, and Sudan. These between them will account for 2.3 billion Muslims, or two-thirds of the world’s total Muslims.

Interestingly, there are 12 countries which will each have over 100 million Christians, and together they will also account for 2.3 billion Christians in 2100: Nigeria, DR Congo, the USA, Ethiopia, China, India, Tanzania, Brazil, Philippines, Uganda, Angola and Mexico. These 12 will then represent 60% of the world’s then 3.8 billion Christians.

I would be curious to hear what people think the implications of that will be.