How Many People Become Muslim or Christian Around the World?
Religious conversion is an important part of the changing religious landscape around the world. Many people ask how many people convert to Islam or Christianity each year and which religion gains more converts. However, there is no reliable worldwide system that records every conversion. Instead, major demographic studies examine religious switching by comparing the religion people were raised in with the religion they identify with as adults.
Two of the world’s largest religions—Islam and Christianity—are often compared when people ask which religion gains more converts.
This leads to an important question:
How many people convert to Islam every year, and how many convert to Christianity?
The honest answer is that there is no reliable worldwide annual count of religious conversions. There is no global registration system that records every person who becomes Muslim or Christian, and many conversions happen privately without a formal ceremony.
However, major demographic studies can provide a much clearer picture by examining religious switching: what religion people were raised in as children compared with the religion they identify with as adults.
The latest major global analysis by the Pew Research Center, published in 2025, examined religious change using surveys from 117 countries and territories. The study compared people’s childhood religious upbringing with their current adult religious identity and found major differences between Christianity, Islam, Buddhism, Hinduism and people with no religious affiliation.
The results are particularly interesting for Christianity and Islam.
Conversion and Religious Switching Are Not Exactly the Same
Before looking at the numbers, it is important to understand the difference between conversion and religious switching.
A conversion usually refers to a person consciously adopting a new religion.
For example:
- A Christian becomes Muslim.
- A Muslim becomes Christian.
- A Hindu becomes Christian.
- A person raised without religion becomes Muslim.
Religious switching is a broader demographic measurement.
A person is considered to have switched if the religion they were raised in during childhood is different from the religion they identify with as an adult.
This can include:
- Conversion from Christianity to Islam
- Conversion from Islam to Christianity
- Conversion from another religion to Islam
- Conversion from another religion to Christianity
- Leaving Christianity and becoming religiously unaffiliated
- Leaving Islam and becoming religiously unaffiliated
- Moving from no religion into Christianity
- Moving from no religion into Islam
It can happen with or without a formal religious ceremony.
This is why the latest global studies generally use the term religious switching rather than simply “conversion.”
Is There an Exact Number of People Who Convert to Islam Every Year?
No authoritative organization currently provides an exact worldwide annual number of people who convert to Islam.
There are several reasons for this.
First, many countries do not officially record religious conversion.
Second, becoming Muslim does not necessarily require registration with a government.
Third, some people change their religious identity privately.
Fourth, different surveys define conversion differently.
A person might identify as Muslim without attending a mosque or completing a formal conversion ceremony. Another person might formally declare the Shahada but not immediately appear in demographic statistics.
Therefore, claims such as:
“10 million people become Muslim every year”
or
“20 million people convert to Christianity every year”
should be treated cautiously unless a reliable methodology is provided.
The best global evidence comes from large population surveys and demographic studies rather than viral social-media claims.
What Does the Latest Global Research Say?
The latest major Pew Research Center analysis published in 2025 studied religious change using surveys from 117 countries and territories.
The researchers compared two things:
- The religion in which adults were raised during childhood
- Their current religious identity
The analysis focused particularly on adults ages 18 to 54, because religious switching tends to occur more frequently earlier in adulthood.
The findings show a striking difference between Christianity and Islam.
Among adults ages 18 to 54 who were raised Christian:
- About 17.1 out of every 100 had left Christianity.
- About 5.5 out of every 100 had entered Christianity after being raised in another religion or with no religion.
- This produced a net loss of 11.6 people per 100 raised Christian.
Islam showed a very different pattern.
Among people raised Muslim, only about 1 in 100 had left Islam, and a similarly small proportion of people from other backgrounds had entered Islam.
As a result, religious switching has had very little net effect on the global size of the Muslim population.
This does not mean that nobody converts to Islam. It means that, at the global level, the number entering and leaving Islam through religious switching is relatively small compared with the enormous size of the Muslim population.
Christianity Has Experienced the Largest Net Loss From Religious Switching
One of the most important findings from the latest global research is that Christianity has experienced the largest net loss from religious switching among the major religious groups studied.
For every 100 adults ages 18 to 54 who were raised Christian:
17.1 left Christianity, while 5.5 entered Christianity.
That produces a net loss of:
11.6 people for every 100 raised Christian.
Most people leaving Christianity do not become Muslims.
This is extremely important because online discussions sometimes create the impression that Christians leaving Christianity are primarily becoming Muslim.
The global data does not support that conclusion.
The largest destination for former Christians is generally the religiously unaffiliated category.
In other words, many people who leave Christianity become:
- Atheist
- Agnostic
- “Nothing in particular”
- Religiously unaffiliated
Some also move to another religion, including Islam, Buddhism, Hinduism or other religious traditions.
Does This Mean Christianity Is Disappearing?
No.
This conclusion would be incorrect.
Christianity remains the largest religious group in the world.
According to Pew Research Center’s global demographic estimates, there were approximately 2.3 billion Christians worldwide in 2020.
Christianity’s global population actually increased from approximately 2.1 billion in 2010 to 2.3 billion in 2020.
However, Christianity’s share of the world’s total population decreased because the global non-Christian population grew faster.
The Christian share of the world’s population fell from approximately 31% in 2010 to 28.8% in 2020.
Therefore, the situation is more complicated than simply saying that Christianity is “growing” or “shrinking.”
Christianity can increase in absolute numbers while declining as a percentage of the global population.
Why Is Christianity Still Growing in Some Parts of the World?
Religious switching is only one factor that determines the size of a religious population.
Other major factors include:
- Birth rates
- Death rates
- Age structure
- Migration
- Population growth
- Religious switching
This is particularly important when comparing Christianity and Islam.
Christianity has experienced significant demographic growth in sub-Saharan Africa, where Christian populations are large and relatively young.
In many African countries, Christianity continues to have strong population growth even while Christianity is losing members through switching in parts of Europe, North America and other regions.
Therefore, global religious demographics cannot be understood simply by counting converts.
How Many People Become Muslim?
Again, there is no reliable worldwide annual number of people who become Muslim.
However, the latest global research provides a very important insight:
Islam has extremely high retention among people raised Muslim.
Approximately 99% of adults ages 18 to 54 who were raised Muslim still identify as Muslim.
Only about 1% have switched out of Islam.
At the same time, a similar proportion of people from other backgrounds have switched into Islam.
This means that religious switching has had only a small net effect on the overall Muslim population.
This is very different from Christianity, where the number leaving through switching substantially exceeds the number entering.
Is Islam the World’s Fastest-Growing Religion Because of Conversion?
Not primarily.
This is one of the most important facts to understand.
Islam was the fastest-growing major religious group between 2010 and 2020, according to Pew Research Center.
The global Muslim population increased from approximately:
1.7 billion in 2010
to
2.0 billion in 2020.
That represents an increase of about 347 million people.
However, the overwhelming demographic explanation for Muslim population growth is not mass conversion.
The major factors are:
- Younger average age
- Higher fertility
- Population momentum
- Demographic structure
Religious switching plays a comparatively small role.
Therefore, saying:
“Islam grew by hundreds of millions because hundreds of millions converted”
would be incorrect.
Most of the increase resulted from demographic factors rather than religious conversion.
Why Is the Muslim Population So Young?
One of the major reasons for Muslim population growth is age structure.
Globally, Muslims have a younger median age than Christians.
A younger population means a larger share of people are in or approaching childbearing ages.
When a religious group has a young population and relatively high fertility, its population can grow rapidly even if conversion rates are relatively low.
This is why demographic studies distinguish between:
Natural increase
and
Religious switching.
Natural increase refers primarily to births exceeding deaths.
Religious switching refers to people changing religious identity.
Islam’s global growth between 2010 and 2020 was driven primarily by natural increase, rather than large-scale conversion.
How Many People Convert From Christianity to Islam?
There is no reliable worldwide annual figure.
Some countries have detailed surveys that allow researchers to estimate religious switching, but there is no global database recording every Christian who becomes Muslim.
However, the global data provides an important clue.
Most people leaving Christianity do not become Muslim.
Instead, many former Christians become religiously unaffiliated.
This means that the global Christian decline caused by religious switching should not be interpreted as evidence that Muslims are receiving all—or even most—former Christians.
The movement is much broader.
How Many Muslims Become Christian?
There is also no reliable worldwide annual number.
Some individual countries and regions have documented cases of Muslims becoming Christians, and some Christian organizations report large numbers of converts.
However, such reports often come from specific organizations, regions or missions and cannot automatically be extrapolated to the entire world.
A credible global estimate requires representative surveys covering large populations.
The available global demographic evidence indicates that switching into and out of Islam is relatively uncommon compared with switching involving Christianity and the religiously unaffiliated.
What Happens to People Who Leave Christianity?
The answer is particularly interesting.
According to global research, most people who leave Christianity do not immediately join another major religion.
Many become religiously unaffiliated.
This category includes people who describe themselves as:
- Atheist
- Agnostic
- No religion
- Nothing in particular
This is one of the most important trends in global religious demographics.
In many Western countries, Christianity has experienced significant losses because people who were raised Christian increasingly identify as having no religion.
The Growth of the Religiously Unaffiliated
The religiously unaffiliated population has become one of the world’s largest religious-demographic categories.
Pew Research Center estimates that the global unaffiliated population reached approximately 1.9 billion people in 2020, representing about 24.2% of the world’s population.
This makes the religiously unaffiliated group larger than every major religious group except Christianity and Islam.
The growth of this category is strongly connected with religious switching.
Among adults ages 18 to 54 who were raised with no religion:
- 7.5 per 100 had left the unaffiliated category.
- 24.2 per 100 had entered it.
That produced a net gain of 16.7 people per 100 raised without religion.
This is larger than the net gain from switching experienced by any major religion.
Christianity vs. Islam: Religious Retention
Religious retention is another useful way to understand the difference between Christianity and Islam.
Retention asks:
Of the people who were raised in a particular religion, how many still identify with that religion as adults?
The latest global research found:
Islam
Approximately 99% of adults ages 18 to 54 raised Muslim remain Muslim.
Christianity
Approximately 83% of adults ages 18 to 54 raised Christian remain Christian.
This is a major demographic difference.
Christianity has a much higher level of religious switching out of the faith, while Islam has extremely high retention.
Does High Muslim Retention Mean Nobody Leaves Islam?
No.
It is important not to exaggerate the data.
Approximately 1% of adults raised Muslim have switched out of Islam in the global analysis.
That represents millions of people when applied to a population of billions.
But as a percentage, it is relatively small.
Similarly, the fact that Christianity has a lower retention rate does not mean most Christians leave Christianity.
The majority of people raised Christian still identify as Christian.
The global figure of approximately 83% retention means that Christianity retains a substantial majority of people raised within the faith.
Which Religion Gains the Most From Conversion?
This question depends on what “gain” means.
If we look only at religious switching, Islam and Hinduism show relatively small movement in both directions.
Christianity experiences a net loss.
Buddhism also experiences a net loss.
The biggest net winner from religious switching is actually:
The religiously unaffiliated population.
This is a crucial point.
Many people who leave Christianity do not become Muslim, Hindu or Buddhist.
They simply leave organized religion.
Why Do People Convert to Islam?
There is no single reason why people become Muslim.
People who convert to Islam may describe different motivations, including:
Belief in One God
Some converts are attracted to the Islamic concept of Tawhid, the belief in the absolute oneness of God.
Interest in the Qur’an
Some people begin studying the Qur’an and become interested in its teachings.
Personal Relationships
Some people encounter Islam through Muslim friends, colleagues, spouses or family members.
Marriage
Marriage can sometimes expose people to another religious tradition, although marriage and sincere religious conversion are not the same thing.
Community
Some people are attracted to the sense of community found in mosques and Muslim communities.
Spiritual Experience
Some converts describe personal spiritual experiences as important in their journey.
Intellectual or Theological Reasons
Some people become interested in Islamic teachings about God, prophets, revelation, morality and the afterlife.
It is important to remember that these motivations differ from person to person.
Why Do People Become Christian?
People who become Christian also have diverse reasons.
These can include:
Faith in Jesus
For many converts, belief in Jesus Christ is central to their decision.
Christian Scripture
Some people study the Bible and become convinced by its teachings.
Personal Relationships
Friends, spouses, colleagues and family members can introduce people to Christianity.
Church Community
Some people are attracted by Christian worship, community and fellowship.
Spiritual Experiences
Some converts describe experiences they interpret as encounters with God.
Missionary Activity
Christian missionary organizations have historically played an important role in spreading Christianity in many parts of the world.
Marriage and Family
Relationships and family circumstances can also influence religious identity.
Again, there is no single explanation for Christian conversion.
Does Migration Cause Religious Growth?
Migration can dramatically change the religious composition of individual countries and regions.
For example, migration can increase the number of Muslims in a European country or increase the number of Christians in another region.
But at the global level, migration does not change the total number of Muslims or Christians.
If a Muslim moves from Pakistan to the United Kingdom, the person is still Muslim.
The Muslim population of one country changes, but the world’s total Muslim population does not increase simply because of migration.
This is why global demographic studies separate migration from religious switching.
What Happened to Christianity Between 2010 and 2020?
Between 2010 and 2020:
- The global Christian population increased from about 2.1 billion to 2.3 billion.
- But Christianity’s share of the world’s population fell from about 31% to 28.8%.
- Christianity experienced significant switching losses in many countries.
- Sub-Saharan Africa became the region with the largest Christian population, surpassing Europe.
This shows why regional analysis matters.
Christianity is declining as a share of the population in many Western countries, while Christianity continues to grow demographically in parts of Africa.
What Happened to Islam Between 2010 and 2020?
The Muslim population increased from approximately:
1.7 billion → 2.0 billion
between 2010 and 2020.
The Muslim share of the world’s population increased from approximately:
24% → 25.6%.
Muslims grew faster than the global population during this period.
However, this growth was overwhelmingly associated with demographic factors rather than a massive wave of conversion.
Christianity and Islam in Africa
Africa is particularly important when discussing future religious demographics.
Sub-Saharan Africa has become home to the world’s largest Christian population by region.
At the same time, it contains one of the world’s largest Muslim populations.
Countries such as Nigeria are especially important because Christianity and Islam both have very large populations.
Religious demographics in Africa are influenced by:
- High fertility
- Young populations
- Urbanization
- Migration
- Religious affiliation
- Conversion
- Education
- Social change
Therefore, Africa is likely to remain one of the most important regions for the future of both Christianity and Islam.
What About Europe?
Europe presents a very different picture.
Many European countries have experienced substantial religious switching away from Christianity.
Countries such as Spain, Sweden, the Netherlands, Germany, the United Kingdom, France and others have seen large shares of people raised Christian becoming religiously unaffiliated.
This does not mean that Christianity has disappeared.
Christian populations remain substantial in many European countries.
However, the percentage of people who actively identify as Christian has declined significantly in many places.
What About the United States?
The United States provides another important example.
Recent Pew Research Center research found substantial religious switching among American adults.
Many Americans who were raised Christian no longer identify as Christian.
At the same time, some people raised without religion or in another religion become Christian.
However, the overall balance remains unfavorable to Christianity.
This demonstrates that religious switching is not simply a European phenomenon.
Is Christianity Growing Through Conversion in Some Countries?
Yes.
The global picture is not uniform.
Pew’s research found that some countries have relatively high rates of people entering Christianity after being raised in another religion or without religion.
For example, Singapore and South Korea have relatively high Christian accession rates.
In Singapore, a substantial share of current Christians say they were raised outside Christianity.
South Korea also has a significant population of Christians who were not raised Christian.
This demonstrates that Christianity can gain converts even while experiencing losses in other countries.
Are There Countries Where Christianity Gains More People Than It Loses?
Yes.
Singapore is an important example.
In the Pew analysis, Singapore had more people entering Christianity than leaving it through religious switching.
However, this does not mean Christianity is growing everywhere.
Religious switching is strongly influenced by local history, culture, demographics and religious composition.
Are There Countries Where Islam Gains More Than It Loses?
Yes, but the overall switching rates are relatively small.
The global research found that Islam is unusual because it has roughly balanced movement into and out of the religion.
In some individual countries, there can be more people entering Islam than leaving it.
In others, the opposite may occur.
The global pattern, however, is one of very high retention and relatively little switching.
What Percentage of the World Is Muslim or Christian?
According to Pew Research Center’s estimates for 2020:
Christianity
Approximately 28.8% of the world’s population identified as Christian.
Islam
Approximately 25.6% of the world’s population identified as Muslim.
Christianity remained the world’s largest religious group, followed by Islam.
The two together represented more than half of the world’s population.
Why Do Population Numbers and Conversion Numbers Get Confused?
This happens frequently in online discussions.
Someone may see that the Muslim population increased by hundreds of millions and assume that hundreds of millions of people converted to Islam.
But population growth can occur through:
Births − deaths + migration + religious switching
At the global level, migration does not change the total size of a religious population.
Therefore, the enormous increase in the Muslim population between 2010 and 2020 cannot be interpreted as the number of converts.
Similarly, Christianity’s total population increased even though Christianity experienced significant net losses from religious switching.
Demography is more complicated than conversion statistics.
Is There a Global Ranking of Conversion Rates?
Not in a way that can reliably answer “how many people convert every year.”
Researchers can compare religious switching rates across countries.
However, different countries have different:
- Census systems
- Survey methodologies
- Definitions of religion
- Cultural environments
- Religious traditions
- Laws
- Social pressures
- Reporting practices
Therefore, comparing a conversion number reported by a church in one country with a mosque organization’s estimate in another country would not necessarily produce a meaningful global comparison.
Why Are Exact Conversion Numbers Difficult to Measure?
There are several methodological problems.
No Universal Registration
Most countries do not require people to register religious changes.
Private Conversion
People may change their beliefs without telling their government, family or religious institution.
Multiple Religious Identities
Some people identify with more than one tradition or retain cultural ties to a religion while adopting another belief system.
Return to Previous Religion
A person may convert, leave the religion and later return. Simple surveys may not capture every change.
Denominational Changes
Moving from Catholicism to Protestantism, for example, may be considered a major change within Christianity but still counts as Christianity in broad global demographic categories.
Social Pressure
In some countries, people may be reluctant to publicly report a change in religion.
For these reasons, global conversion numbers should always be interpreted carefully.
The Most Important Global Finding
Perhaps the most important finding is not that “Islam gains more converts” or “Christianity loses more converts.”
The bigger story is this:
Religious switching is increasingly contributing to the growth of people with no religious affiliation, while Christianity has experienced the largest net losses from switching among the world’s major religions.
At the same time:
Islam has extremely high retention and has experienced relatively little net change from religious switching.
And:
Muslim population growth has been driven primarily by demographic factors such as younger age structure and higher fertility rather than mass conversion.
This gives us a much more accurate picture than viral conversion claims.
Christianity vs. Islam: Global Religious Switching
| Category | Christianity | Islam |
|---|---|---|
| Global population in 2020 | About 2.3 billion | About 2.0 billion |
| Share of global population | About 28.8% | About 25.6% |
| Retention among adults 18–54 | About 83% | About 99% |
| Religious switching | Relatively common | Relatively uncommon |
| Overall switching effect | Significant net loss | Small net effect |
| Main destination for many leavers | Religious unaffiliation | Varies |
| Main driver of recent global population growth | Demography, especially in Africa | Young age structure and fertility |
| Exact annual global conversion count | Not available | Not available |
So, Who Gets More Converts: Islam or Christianity?
There is no scientifically reliable global annual number that allows us to say:
“X million people convert to Islam every year and Y million convert to Christianity.”
Such a claim would give a false impression of precision.
What the strongest available global demographic evidence does tell us is:
- Christianity experiences substantial religious switching out of the faith.
- Christianity also receives converts, but not enough to offset its global switching losses.
- Islam has exceptionally high retention.
- Switching into and out of Islam is relatively uncommon.
- The number of people entering Islam and leaving Islam is relatively balanced at the global level.
- The biggest net movement from religious switching is toward having no religious affiliation.
- Muslim population growth is driven mainly by demographic factors rather than mass conversion.
- Christian population growth or decline varies greatly by region.
Does This Mean Conversion Is Unimportant?
No.
Even if conversion represents a relatively small proportion of global population change, it can be extremely important to individuals and communities.
A single person’s religious conversion can affect:
- Family relationships
- Marriage
- Community
- Identity
- Daily practices
- Worship
- Lifestyle
- Education
- Social relationships
Therefore, demographic statistics should not be interpreted as saying that individual conversions are insignificant.
What Should We Learn From the Data?
The global religious landscape is changing, but the changes are not as simple as social-media debates often suggest.
Islam is growing rapidly in population size, but mainly because of demographic factors.
Christianity remains the world’s largest religious group, but it is losing a significant share of people through religious switching in many countries.
The religiously unaffiliated population is growing rapidly because many people are leaving religious traditions, particularly Christianity.
At the same time, Christianity continues to grow demographically in parts of Africa and other regions, while Islam maintains very high retention across the countries studied.
The future of global religion will therefore be shaped by a combination of:
- Birth rates
- Age structure
- Religious retention
- Conversion
- Disaffiliation
- Migration
- Education
- Urbanization
- Social change
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