Why Islam Grew (And Christianity Didn’t) Around The World In Just A Decade
NEW YORK – The global population grew between 2010 and 2020, and with it, most of the world’s religious groups — though not all at the same rate.
According to a new report released Monday from Pew Research Center, Christianity remains the world’s largest religion, but it did not keep pace with overall population growth over the past decade.
Drawing on data from more than 2,700 censuses and surveys across 117 countries, Pew found that while the number of Christians rose by 122 million — reaching 2.3 billion — their share of the global population declined by 1.8 percentage points to 28.8%.
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In several Western countries, Christians now make up less than half of the population. That includes the United Kingdom (49%), Australia (47%), France (46%) and Uruguay (44%).
In each of these countries, religiously unaffiliated people now account for 40% or more of the population, while smaller religious groups such as Muslims, Hindus, Buddhists, Jews and others together make up 11% or less.
The Pew report identifies Muslims as the fastest-growing religious group during this decade span. Their numbers increased by 347 million — more than all religious groups Pew surveyed combined.
As a result, Muslims now make up 25.6% of the global population, up 1.8 percentage points from a decade earlier.
Religion continues to play a significant role in shaping cultures and communities around the world, especially in Muslim-majority nations. The spread of Islam — dubbed “the world’s fastest growing religion” for years now — has been driven by higher fertility rates both in the Middle East and across the West. Muslims (along with Hindus) have been the least likely to gain or lose adherents from something called “religious switching.”
By contrast, Buddhists were the only major religious group to experience a decline in absolute numbers. The global Buddhist population fell by 19 million to 324 million, representing 4.1% of the world population — a drop of 0.8 percentage points.
“Typically, change in population sizes is driven by demographic factors, including differences in groups’ fertility and mortality patterns, as well as their age distribution (also called ‘age structure’),” the report said. “Populations that are relatively young, on average, and have more children typically expand more quickly than those that are relatively old or have large numbers of people who die prematurely due to wars, diseases or famines.”
One of the most notable shifts is the rise in the number of people with no religious affiliation, often referred to as “nones.” While the rise of the nones is nothing new, this latest Pew survey confirms some of the data released over the past few years.
Pew said in its latest report that this group was the only one — aside from Islam — to grow as a percentage of the global population over the decade.
The number of religiously unaffiliated individuals increased by 270 million, reaching 1.9 billion and accounting for 24.2% of the world’s population—nearly a full percentage point higher than in 2010.
The United States is now home to the world’s second-largest population of religiously unaffiliated people, following China, which is a communist nation. It has surpassed Japan in this category.
“The growth in the share of people around the world who are religiously unaffiliated is striking because low fertility and an older age structure put religiously unaffiliated people at what demographers call a disadvantage compared with the higher fertility and younger age of religiously affiliated people, globally,” the report said.
Sub-Saharan Africa has emerged as a major center for Christianity, surpassing Europe. As of 2020, 30.7% of the world’s Christians lived in sub-Saharan Africa, compared to 22.3% in Europe.
Globally, 75.8% of people still identified with a religion in 2020. However, the share of the global population with any religious affiliation has declined slightly, down from 76.7% in 2010. Conversely, the share without a religious affiliation rose from 23.3% to 24.2%.
While demographic trends typically favor religious groups due to higher fertility rates and younger populations, these unaffiliated people are growing due in part to religious switching, primarily among Christians.
The growth of religious nones, for example, is “striking” because they are at a ‘demographic disadvantage,’” the report said.
However, Pew said unaffiliated people “continued to grow as a share of the global population because many affiliated people around the world – primarily Christians – are ‘switching’ out of religion.”
Clemente Lisi is the executive editor of Religion Unplugged.