Muslim Majority countries will (probably) reach 25% of the world by 2100

Out of nearly 240 countries in the world (depending on how you count them), there are 51 where Muslims form the majority. Altogether their populations (Muslims and non-Muslims together) totaled 319 million. In 2025, the populations of the countries are estimated to be 1.6 billion. By 2050, their populations will number 2.2 billion, and there will be 2.8 billion Muslims on the planet–so roughly half a billion Muslims will be found in Muslim-minority countries (like Nigeria, India, etc.) By 2100, Muslim-majority countries will have total populations of 2.8 billion.

Christians today number 92.9 million in these countries, 24.9 million of them considered Evangelicals by the Operation World definition (both these numbers derived from Joshua Project’s current data, for ease of reproduction). That makes Christians about 5% of these countries, and Evangelicals a little more than 1%.

The growth in raw numbers might look a little astonishing, and even frightening. But Islam tends to be centered in countries with rapidly growing populations, and many of those population growth rates are now crashing. The annual growth rates show this in stark relief: from 1950 to 1975, Muslim-majority populations grew at 1.9% per annum. By 2025, this had slowed to 1.2% yearly. It has continued to decline, and by 2100 is expected to be just 0.2% per year.

By 2100, 24 of the 51 Muslim-majority countries will have negative growth rates—their populations will be in decline. Bangladesh is an example of this: from 37.8 million in 1950, their population has risen to 178 million today and is expected to peak around 200 million in 2050, and then decline back to 173 million by 2100. At the turn of the century, only 4 Muslim-majority countries are expected to be growing at rates faster than 1% per year: Niger (192m, #12 largest population in the world in 2100), Iraq (155 million, #17), Cote d’Ivoire (103m, #24), Somalia (78.9 million, #33), and Senegal (64.8 million, #41).

This trend line will drive Islam’s global share of world population: it will increase, but increasingly slowly. In 1900, Muslim-majority countries made up 12.5% of the world’s population. By 2025, this will have grown to 20.6% of the world. It is continuing to grow, but far more slowly: by 2100, if these projections hold true, Muslim-majority countries will make up 25.1% of the world’s population.

In 2100, there will be 8 Muslim-majority countries with over 100 million people, and together they will make up over half—nearly 60%–of all the Muslims in the world. They include (in descending order of 2100 population): Pakistan, Indonesia, Egypt, Niger, Bangladesh, Iraq, and Sudan. Any change in the religious trajectory of these countries would change global dynamics. These countries are also home to over 59 million Christian believers (according to Joshua Project, and not taking into account recent numbers from Disciple-making Movements).

(By way of context, the top 5 countries in 2100 will be, in order: India, 1.5b; China, 1.0b; Nigeria, 0.8b; USA, 0.4b; DR Congo, 0.3b).