A new report from the Pew Research Center reveals that, despite remaining the world's largest religious group, Christianity’s share of the global population has decreased over the past decade.
The analysis, which examined data from 2,700 censuses and surveys, shows that the number of Christians worldwide increased by 121.6 million from 2010 to 2020, reaching approximately 2.3 billion people. However, as a proportion of the total global population estimated at about 7.8 billion in 2020, Christians declined by 1.8 percentage points to 28.8%.
In contrast, the Muslim population grew by 347 million during the same period, reaching 2 billion people. Their share of the global population increased by 1.8 percentage points to 25.6%, making Muslims the fastest-growing religious group globally.
“Religious disaffiliation is the main driver of the decline in the Christian share of the global population," the researchers noted. “Religious disaffiliation — primarily of people leaving Christianity — also is the main driver of the growth of religiously unaffiliated populations.”
Religiously unaffiliated individuals globally increased by 270.1 million between 2010 and 2020, reaching a total of 1.9 billion. They now comprise nearly a quarter of the world's population, accounting for 24.2%.
To analyze religious disaffiliation and switching, researchers examined surveys from 117 countries, focusing on adults aged 18 to 54. They found that “for every adult in that age group who says they joined a religion after having been raised without a religion, 3.2 moved in the other direction — they left religion altogether after having been raised in one.” As a result, “the religiously unaffiliated category has had the largest net gain due to switching.”
The study also revealed that “Christians have experienced the biggest net losses from switching (3.1 have left for every 1.0 who has joined). Most former Christians no longer identify with any religion, but some now identify with a different religion,” the researchers stated.
In the United States, about 101 million people identified as religiously unaffiliated in 2020, marking a 97% increase over the previous decade.
Globally, China led the world with the highest number of religiously unaffiliated people, with “some 90% of that country’s population, or 1.3 billion people, identified as religiously unaffiliated.”
The report also highlighted significant geographic shifts: sub-Saharan Africa now has the largest number of Christians, surpassing Europe. In 2020, 30.7% of the world’s Christians lived in sub-Saharan Africa, while only 22.3% lived in Europe.
While most countries remain Christian-majority, the report noted that in the past decade, the Christian population dropped below 50% in several countries, including the United Kingdom (49%), Australia (47%), France (46%), and Uruguay (44%). Additionally, in countries like the Netherlands, Uruguay, and New Zealand, religiously unaffiliated people became a majority with 54%, 52%, and 51% respectively.
