Islam experienced the most rapid growth among all major religious groups worldwide between 2010 and 2020, with its global population increasing by 347 million people to reach 2.0 billion. This expansion significantly outpaced the growth of other faiths, including Christianity, and the overall global population increase.¹ The primary drivers of this substantial growth are demographic factors: notably, higher birth rates and a younger median age within Muslim communities globally.¹ While religious conversion contributes to the diversification and growth of Muslim communities in specific regions, its net global impact on the overall population increase is modest, as the number of individuals embracing Islam is largely offset by those who leave the faith.¹ This report details these trends, providing a nuanced understanding of the forces reshaping the global religious landscape.

1. Introduction: The Global Landscape of Religious Change

The global religious landscape is undergoing significant transformations, with Islam emerging as a prominent force in demographic shifts. Between 2010 and 2020, Islam solidified its position as the world’s second-largest religious group, following Christianity, while demonstrating the fastest growth rate among all major faiths.¹ During this decade, the global Muslim population expanded by an impressive 347 million individuals, reaching a total of 2.0 billion people by 2020. This growth rate, at 21%, was twice as fast as the overall global population expansion of 10% during the same period.⁴ In comparison, the Christian population grew by 122 million, but its global share declined due to high rates of disaffiliation, and other groups like Buddhists saw an absolute decrease in numbers.¹

This rapid expansion has led to a notable rebalancing of global religious adherence. In 2010, Muslims constituted 23.9% of the world’s population, while Christians accounted for 30.6%. By 2020, the Muslim share had risen to 25.6%, and the Christian share had decreased to 28.8%.¹ This narrowing gap between the two largest religious groups underscores a fundamental, long-term shift in global religious composition. Such a demographic evolution carries significant implications, potentially influencing geopolitical dynamics, socio-cultural interactions, and resource allocation in regions experiencing pronounced changes in their religious makeup. The evolving religious composition of nations may necessitate increased interfaith dialogue, reshape political landscapes in diverse societies, and present both new challenges and opportunities for international relations. Furthermore, the concurrent rise of religiously unaffiliated individuals globally ² suggests a complex, multi-directional evolution of religious identity, indicating that changes are not merely a zero-sum game between traditional faiths.

This report aims to dissect the underlying reasons for Islam’s rapid growth, meticulously differentiating between the predominant role of natural population increase and the more nuanced, regionally specific contributions of religious conversion. By exploring the motivations behind conversion, the analysis seeks to provide a comprehensive understanding of this dynamic global phenomenon.

2. Overall Muslim Population Growth: Trends and Statistics (2010-2020)

The period between 2010 and 2020 witnessed a substantial quantitative expansion of the global Muslim population. The number of Muslims worldwide increased from 1.7 billion to 2.0 billion, marking a 21% growth rate. This growth significantly outpaced the global population, which expanded by 10% over the same decade.⁴ The absolute increase of 347 million Muslims during this period was greater than the combined growth of all non-Muslim religions, which collectively added 248 million people.¹

Regional patterns reveal varied rates of Muslim population growth. North America recorded the highest rate of increase, with the Muslim population growing by 52% to 5.9 million in 2020. Sub-Saharan Africa followed with a 34% increase, reaching 369 million Muslims.⁴ While these regions exhibited the highest growth rates, the largest concentrations of Muslims in 2020 remained in the Asia-Pacific region (1.2 billion), the Middle East-North Africa (414 million), and Sub-Saharan Africa (369 million).¹

There has been a subtle but important geographical redistribution of the global Muslim population. Between 2010 and 2020, the proportion of the world’s Muslims residing in Sub-Saharan Africa increased by 2 percentage points, reaching 18% of the global total. Conversely, the Asia-Pacific region saw a slight decrease in its share, holding 59% of all Muslims in 2020, down by 2 percentage points.⁴ This indicates that while Asia-Pacific remains the demographic heartland, Sub-Saharan Africa is rapidly gaining prominence in the global Muslim population landscape.

Country-specific data further illustrates these dynamics. Kazakhstan, Benin, and Lebanon experienced substantial increases in their Muslim population share, each rising by at least 5 percentage points. In Kazakhstan, this was partly driven by the departure of Christians, whose share in the population fell from 27% to 19%.⁴ Lebanon’s increase was significantly influenced by an influx of 880,000 foreign-born Muslims between 2010 and 2020.⁴ In contrast, Tanzania and Oman saw a decrease in their Muslim share, attributed in Tanzania to lower Muslim fertility rates compared to non-Muslims, and in Oman to a significant increase in its foreign-born population.⁴ Even in Europe, countries like Sweden, Austria, and Germany experienced modest growth in their Muslim populations, largely due to immigration, including Syrian war refugees, and higher fertility rates among Muslims, though these increases did not meet the 5-point threshold for substantial change.⁴

The observation that Muslim population growth is not uniform but varies significantly by region underscores the influence of complex socio-political events and migration patterns, particularly in non-Muslim majority areas. This suggests that future projections of Muslim population growth must integrate factors beyond just internal demographic rates, such as global conflicts, economic opportunities, and associated migratory flows. These dynamics also highlight potential challenges and opportunities for integration in host countries as their religious compositions evolve.

Table 1: Global Religious Population Change (2010-2020)

Source: Pew Research Center estimates based on.¹

3. Primary Drivers: Demographic Factors

The overwhelming majority of Islam’s recent growth is attributable to robust demographic factors, which fundamentally shape population dynamics. These factors create a powerful demographic momentum that ensures sustained expansion of the Muslim population.

The foremost contributor is the consistently higher fertility rates among Muslim women compared to other major religious groups. Between 2015 and 2020, Muslim women had an average of 2.9 children in their lifetime, a significantly higher figure than the 2.2 children per non-Muslim woman. For context, Christians had the next highest fertility rate at 2.6.¹ This sustained higher birthrate directly translates into a continuous influx of new individuals born into the faith, forming the bedrock of the population increase.¹

Complementing this, the younger median age of the Muslim population further fuels its growth. In 2020, the global median age for Muslims was 24, which is nine years younger than the non-Muslim median of 33.¹ This youthful demographic structure means that a larger proportion of the Muslim population is either currently in or approaching their prime reproductive years. This age distribution inherently contributes to higher birth rates and ensures a strong population momentum for decades to come. The observation that Muslim culture naturally tends to embrace larger family structures compared to more secular cultures further supports this demographic outcome.⁶

Moreover, a significant portion of the Muslim population is geographically concentrated in regions that are projected to experience rapid overall population growth in the coming decades. Notably, Sub-Saharan Africa is home to 18% of global Muslims, and this region, along with the Middle East-North Africa, is characterized by generally higher birth rates across all populations.¹ This geographic distribution amplifies the impact of the already high fertility rates within Muslim communities, contributing disproportionately to the global increase.

Crucially, the low disaffiliation rates among Muslims play a vital role in retaining this demographic growth. While some individuals do leave Islam, the rate of disaffiliation—estimated at about 1% of those raised Muslim—is remarkably low. This modest loss is largely offset by a comparable influx of converts globally.¹ This stability in adherence across generations, combined with high birth rates, ensures that the demographic gains are largely retained within the faith.³ This contrasts sharply with the experiences of other major religions, particularly Christianity in Europe and North America, which have seen significant declines due to high rates of disaffiliation.²

The consistent identification of higher birth rates and a younger median age as the primary drivers, with conversion playing a globally minor role, indicates that Islam’s growth is largely self-perpetuating. It is driven by internal demographic dynamics rather than widespread ideological shifts or external proselytization efforts. This suggests that any attempts to influence religious demographics would be largely ineffective if they do not account for these fundamental fertility and age structures. The growth of Islam appears robust and predictable based on current demographic trajectories, establishing it as a significant long-term factor in global population projections. The enduring strength of intra-generational transmission of faith, where Islam persists strongly through generations despite various societal temptations or difficulties, further reinforces this demographic resilience.⁶ This mechanism of growth also highlights a divergence in the challenges faced by different religious groups. While Islam focuses on managing the needs of a young, expanding population, Christianity and other faiths grapple more with retention and addressing reasons for disaffiliation. The rise of the “religiously unaffiliated” is a significant global trend affecting many faiths, but its net impact on Islam’s population change is considerably less pronounced.²

4. Secondary Factor: The Role of Religious Conversion

While demographic factors are the primary drivers of Islam’s global growth, religious conversion plays a distinct and regionally significant role, contributing to the diversification and vitality of Muslim communities, particularly in Western contexts. It is important to note that, globally, religious conversion has a modest net impact on the overall Muslim population. Pew Research data indicates that the number of people converting to Islam is roughly similar to those leaving the faith.¹ Between 2015 and 2020, there was a net gain of approximately 420,000 more people converting to Islam than leaving it.⁷ This figure is relatively small when compared to the overall population increase of 347 million Muslims during the 2010-2020 decade.¹

Looking ahead, a 2015 Pew Research Center study projected a modest net gain of 3.22 million adherents through religious conversion for Islam between 2010 and 2050, with the vast majority (2.9 million) expected to come from Sub-Saharan Africa.⁷ Historically, conversion to Islam was sometimes a collective process, influenced by territorial expansion and economic incentives, such as access to Muslim trade networks for merchants.⁸ However, the contemporary context, especially in the West, presents different dynamics and motivations for conversion.⁸

Regional statistics provide a more granular view of conversion trends:

• United States: An estimated 25% of American Muslims are converts, with a notable predominance of African Americans and women among them.⁷ Observers estimate that between 20,000 and 30,000 Americans convert to Islam annually.⁷ A distinctive trend in the U.S. is that the number of converts to Islam is roughly equal to the number of U.S. Muslims who leave the religion, a pattern unlike other faiths in the country where departures typically exceed conversions.⁷ Approximately 77% of new converts in the U.S. come from Christianity, while 19% were previously religiously unaffiliated.⁷
• United Kingdom: Around 5,000 to 6,000 individuals convert to Islam per year in Britain, with the majority being women.⁷ An earlier 2001 census indicated an increase of 60,000 conversions in the United Kingdom.⁷ Converts in Britain frequently report experiencing hostility from their families.⁷
• France: Experts indicate that conversions to Islam have doubled over the past 25 years in France, with approximately 100,000 converts among the country’s six million Muslims.⁷
• Other Regions: In some countries with strict Islamic laws, apostasy can lead to severe punishments, which contributes to lower rates of religious switching.³ An independent survey in Iran in 2020 revealed a diverse religious landscape, including 32% Shia, 5% Sunni, 3% Sufi, 9% atheists, 8% Zoroastrians, 7% spiritual, and 1.5% Christian, suggesting internal religious diversity and some shifts within a predominantly Muslim nation.¹⁰

The data clearly indicates that while conversion does not drive global Muslim population growth on the same scale as birth rates, it remains a notable and ongoing phenomenon in specific Western contexts. The “net positive” for Islam in terms of religious switching, even if slight globally, is a significant characteristic that distinguishes it from many other religions experiencing net losses. This suggests that the narrative around Islam’s growth must be geographically sensitive. While demographic factors dominate the global picture, conversion is a meaningful aspect of Muslim community development and identity in certain Western nations, contributing to the increasing diversity within these communities. This also highlights the differing dynamics of religious adherence and switching in secularized Western societies compared to Muslim-majority regions.

The consistent mention of women and African Americans as prominent convert groups in the U.S. and U.K. is not coincidental. This points to specific socio-cultural factors at play. For African Americans, historical connections to Islam ¹¹ and an attraction to its message of peace and social justice, including within prison systems and hip-hop culture, are frequently cited as motivations.¹² For women, reasons such as seeking stability and discipline are often noted.⁸ This indicates that conversion is frequently a response to particular societal experiences or needs within distinct demographic segments. This perspective moves beyond mere statistics to explore the social fabric of conversion, suggesting that Islam offers something uniquely appealing to these groups, whether it is a sense of identity, community, or a structured framework for navigating social challenges. Understanding these specific demographics can inform support systems for new converts and illuminates the diverse pathways individuals take to embrace the faith.

Table 2: Regional Conversion Statistics to Islam (Selected Countries)

Source: Pew Research Center estimates and various studies based on.¹

5. Motivations for Conversion to Islam

Individuals are drawn to Islam for a complex array of reasons, often driven by a combination of spiritual, intellectual, and societal factors. The decision to convert is rarely singular but rather a multifaceted journey of personal discovery and alignment.

Spiritual Motivations

A fundamental impetus for many converts is a profound search for purpose and meaning beyond materialism. In modern secular societies, despite their comforts, many individuals report feeling spiritually empty and lacking direction. They describe a void that wealth, entertainment, or career success alone cannot fill, leading them to seek inner peace and answers to fundamental life questions.¹³ Islam offers a compelling alternative: a life centered on spiritual purpose, devotion to God, and clear ethical guidance. This framework often leads to a renewed sense of direction and profound inner peace, with many converts describing their acceptance of Islam as a feeling of “coming home” to something their soul was always seeking.¹³

Another powerful spiritual draw is the direct connection to God that Islam offers. Unlike some other faiths, Islam does not feature an institutional priesthood, emphasizing instead a direct, personal relationship with God (Allah) through prayer and supplication without intermediaries. This direct access and personal responsibility in worship are deeply empowering for seekers of truth.¹³ Regular engagement in acts of worship, such as prayer, Qur’an recitation, and remembrance of God (dhikr), often leads to experiences of tranquility (

sakīnah), reduced anxiety, and increased contentment, as promised in the Qur’an.¹³ Furthermore, conversion is frequently perceived as a fresh start, offering

hope and forgiveness for past sins, thereby lifting heavy burdens from individuals’ hearts.¹³

Intellectual Motivations

The uncompromising monotheism (Tawhid) at the core of Islam is a significant intellectual appeal. The simple creed, “There is no god but God (Allah), and Muhammad is His Messenger,” presents a clear and straightforward concept of divine oneness, free from complex doctrines or mysteries found in some other faiths, such as the Trinity.¹³ Many converts find Islamic theology logically satisfying and accessible to ordinary understanding, often describing their acceptance as a “return” to an innate, intuitive truth about God (

fitrah).¹³

Islam also appeals to those who value a fusion of faith and reason. It encourages the use of intellect in reflecting on creation and revelation, rather than demanding blind faith. This approach resonates with individuals from skeptical or secular backgrounds who seek clarity, verification, and answers to their doubts.¹³ Scholars have noted Islam’s creed as “so precise, so stripped of all theological complexities and so accessible to the ordinary understanding” that it possesses a “marvellous power of winning its way into the consciences of men”.¹³

The authenticity and meticulous preservation of the Qur’an for over 1400 years, coupled with its linguistic beauty, are often decisive factors. Many new Muslims describe reading the Qur’an as a profoundly moving experience, feeling as if the words are “speaking directly to me”.¹³ The Qur’an’s challenge to produce a chapter like it, a challenge that remains unmet, further appeals to those from skeptical backgrounds seeking intellectual rigor.¹³

Societal and Personal Motivations

A powerful draw for many converts, particularly in the West, is Islam’s egalitarian ethos and message of universal brotherhood. Islam teaches the equality of all humans before God, irrespective of race, ethnicity, or social class.¹³ This principle, where only piety and good character truly matter, stands in stark contrast to experiences of racism, discrimination, or alienation that some converts may have faced in other environments.¹³ Malcolm X’s astonishment at the genuine interracial harmony he witnessed during his Hajj pilgrimage serves as a powerful testament to this lived reality within the global Muslim community (ummah).¹³ The egalitarian nature of Islamic rituals, such as praying shoulder-to-shoulder without distinction, reinforces this unity, offering a profound sense of belonging and community.¹³

Beyond theological ideals, Islam offers a tangible attraction as a complete way of life that brings discipline, structure, and healthy habits. Many individuals seeking order and direction for their personal lives find that Islam provides a clear framework for daily living. Practices like the five daily prayers, dietary guidelines, and a comprehensive moral code instill rhythm and self-control, aiding in breaking undesirable habits and fostering personal growth.⁸ This holistic guidance, covering aspects from personal hygiene to business ethics, is appreciated as a comprehensive path to a good life.¹³

Converts are also drawn to Islam’s moral clarity and strong stance on justice. The faith provides clear guidance on right and wrong, emphasizing honesty, charity, kindness, and the sanctity of life, while actively prohibiting exploitation and injustice.¹³ The concept of Zakat (obligatory charity) as a system for social equity is particularly appealing to many.¹³ Furthermore, conversion can represent a profound

personal transformation and an act of identity formation or rebellion, leading to an enhanced sense of self and a disciplined lifestyle.⁸ For some, it offers stability after personal crises, addiction, or restrictive relationships.⁸ While less prevalent than intrinsic reasons,

social influence or marriage can also play a role, where encouragement or pressure to convert arises from a spouse or friends.⁸ Finally, many converts describe their decision as being

“meant to be” or a “part of God’s plan,” feeling a divine calling that forms a satisfying narrative for their spiritual journey.⁸

The observation that many converts seek purpose beyond materialism and find a “complete way of life” in Islam suggests that the faith appeals to a contemporary yearning for order, meaning, and ethical clarity in societies often perceived as secular, unmoored, or morally relativistic. This indicates that Islam is not merely a religious choice but often a lifestyle choice that addresses perceived deficiencies in modern living. This could signify a growing segment of the global population that is disillusioned with aspects of modern Western society and is actively searching for structured, value-driven alternatives.

Furthermore, the emphasis on uncompromising monotheism and the fusion of faith and reason as intellectual appeals is significant. Converts frequently express dissatisfaction with complex doctrines in former faiths and appreciate Islam’s logical clarity and encouragement to question. This indicates that a segment of converts is intellectually driven, seeking a faith that aligns with rational inquiry rather than demanding blind adherence. This challenges the common perception that religious conversion is solely an emotional or social phenomenon. For a notable portion of converts, particularly those from skeptical or secular backgrounds, Islam’s intellectual coherence and its emphasis on a direct, unmediated relationship with God are powerful attractors. This highlights a potential area of growth for Islam among those who value intellectual rigor alongside spiritual fulfillment.

Table 3: Key Motivations for Converting to Islam

Source: Various studies and convert testimonials based on.⁸

6. Conclusion and Outlook

The analysis unequivocally demonstrates that Islam was the world’s fastest-growing major religion between 2010 and 2020. This substantial expansion, which saw the global Muslim population increase by 347 million to 2.0 billion, is primarily attributable to robust demographic factors: consistently higher fertility rates and a significantly younger median age among Muslim populations worldwide.¹ These internal dynamics, particularly pronounced in high-growth regions such as Sub-Saharan Africa and South Asia, create a powerful demographic momentum that drives the majority of Islam’s growth.

While often a subject of public discourse, religious conversion plays a more nuanced role. Globally, the net impact of conversion on the overall Muslim population is modest, with the number of individuals embracing Islam largely balanced by those who leave the faith.¹ However, conversion is a significant phenomenon that contributes to the growth and diversification of Muslim communities in specific Western countries, notably the United States, the United Kingdom, and France. These conversions are driven by a complex interplay of spiritual quests for meaning and purpose, intellectual appeals to monotheism and reason, and societal attractions such as Islam’s egalitarian ethos and its provision of a disciplined way of life.⁷ The distinct demographic profiles of converts in these regions, such as the prevalence of women and African Americans, highlight the specific socio-cultural contexts that make Islam appealing to certain segments of the population.

Based on current trends, Islam is projected to continue its rapid growth. Projections indicate that the number of Muslims could reach 2.9 billion, or 31.1% of the global population, by 2060.⁷ This ongoing demographic momentum will continue to reshape the global religious landscape, influencing social dynamics, international relations, and cultural exchanges worldwide. The increasing visibility and influence of Muslim communities globally will be a defining feature of the 21st century. Governments, international organizations, and civil society groups will need to adapt to and understand these demographic realities, which will impact everything from urban planning and social services to foreign policy and interfaith relations. The findings presented in this report provide critical foresight for strategic planning in a rapidly changing world.

Despite the rise of secularism and disaffiliation observed in many parts of the world, particularly in wealthy countries ², Islam demonstrates remarkable resilience. Its low disaffiliation rates and a net positive conversion rate, albeit modest globally, stand in contrast to the challenges faced by some other major faiths.¹ The motivations cited by converts—ranging from spiritual fulfillment and intellectual clarity to the desire for a structured way of life—suggest that Islam offers a compelling alternative to perceived shortcomings of modern secular societies. This indicates the enduring appeal of structured religious belief for a significant portion of the global population, even in an increasingly secularized world. It suggests that for many, faith provides answers and frameworks that secularism does not, leading them to embrace or retain religious identities. This challenges the notion of a universal decline in religiosity, instead pointing to a more complex, differentiated landscape where some faiths are growing robustly while others face decline.