Despite remaining the largest religious organization, the Christian share of the world’s population shrinks: Research

Muslims are the fastest growing religious organization

By Leonardo BlairSenior Reporter Thursday, June 12th, 2025

A new Pew Research Center report shows that while Christianity remains the world’s largest religious organization, the percentage of global population rise has declined over the past decade, primarily because of those apart from their faith.

The report is based on an analysis of a 2,700-person census and survey, showing that the world Christian population has increased by 121.6 million between 2010 and 2020, reaching approximately 2.3 billion. Christians fell 1.8 percentage points to 28.8% in 2020, with a share of the world’s population estimated at around 7.8 billion.

Meanwhile, the world Muslim population reached 2 billion, a rise of 347 million. The global population share rose 1.8% to 25.6%. The study also recognized Muslims as the fastest growing religious organization in the world.

The biggest factor in the decline in Christian share in the world’s population was religious condemnation, researchers noted. They found that even if more people grew up in religious affiliations than those who are not in Christianity, more people who grew up in faith are beginning to identify as more religiously unrelated than those who are currently identifying with religion.

Pew’s research shows that those that are not religiously related are atheists, agnostics, or those who identify as “nothing in particular.”

“Religious inconsistencies are the main drivers of the decline in Christian share in the world’s population. Religious inconsistencies among people who leave Christianity are also a major factor in the growth of religiously unrelated groups,” the researchers said.

The number of individuals around the world identified as unreligiously affiliated with each other, an increase of 270.1 million between 2010 and 2020, totaling 19 billion. They represent almost a quarter or 24.2% of the world’s population

To better understand the problems of religious inconsistency and religious switching, researchers looked into surveys from 117 countries.

“We use data from adults ages 18 to 54 to capture the switching that occurred recently. Religious switching can occur at any age, but it is more common in life,” they pointed out.

“We found that 3.2 moved in the opposite direction for all adults of that age group who say they joined the religion after being raised without religion. “As a result, based on this set of measures, religiously unrelated categories gained the greatest net profits from the switch.”

And the opposite was true of Christianity.

“Christians experienced the biggest net loss from the switch (3.1 remaining for every 1.0 participants).

As of 2020, China is leading the world with the most unreligiously affiliated people. Approximately 90% of the country’s population, or 1.3 billion, have been identified as unrelated.

Following second place in the US, the company identified roughly 111 million people as religiously unrelated in 2020, reflecting a 97% increase over the past 10 years.

It has also been pointed out that sub-Saharan Africa currently has the largest population of Christians, surpassing Europe. In 2020, 30.7% of the world’s Christians lived in sub-Saharan Africa, while only 22.3% of Europe lived.

While most countries, about 120 countries, remained the majority of Christian countries, this study showed that religious plunder was slowly changing the religious landscape.

Christian populations fell below 50% in the UK (49%), Australia (47%), France (46%) and Uruguay (44%), the report says.

“In each of these locations, religiously unrelated people make up more than 40% of the population, with smaller religious groups, such as Muslims, Hindus, Buddhists, Jews or supporters of other religions (total), accounting for less than 11%,” the researchers said.

Over the period of analysis, religiously unrelated people were majority in the Netherlands (54%), Uruguay (52%) and New Zealand (51%).

In 2022, Pew’s survey found that if the pace at which Christians abandon their faith before the age of 30 accelerates beyond their current pace, they would ban restrictive events such as wars and economic recessions if they would no longer be able to become the majority of Christian nations in 2045.

“Of course, events other than models of research, such as wars, economic recession, climate crisis, changing immigration patterns, and religious innovation could reverse current trends in religious switching, leading to the revival of Christianity in the United States,” the researchers said. “However, there is no current switching pattern that can be factored into a mathematical model to project such results.”