Is Islam the Fastest-Growing Religion, and Does That Prove It Is True?

From 2010 to 2020, Muslims were the fastest-growing major religious group in the world, in the count Pew Research Center published on 9 June 2025. Pew traces that rise to a young population and a high birth rate, not to a wave of conversion. A larger number does not show that a religion is true. Matthew 7:13–14Matthew 7:13 · King James VersionEnter ye in at the strait gate: for wide is the gate, and broad is the way, that leadeth to destruction, and many there be which go in thereat:Matthew 7:13 · King James VersionOpen the Source says the road that leads to life is narrow, and that few find it.

Key Points

• Pew’s report of 9 June 2025 says the Muslim population increased by 347 million in that decade, a larger gain than all other religions combined, and that the Muslim share of the world reached 25.6 percent.
• The same report says Christians remained the largest group. Their count rose by 122 million, to 2.3 billion, while their share of the world fell 1.8 points, to 28.8 percent.
• The companion page on causesFactors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Muslim population growth is largely driven by Muslims’ relatively young age structure and high fertility rate.Factors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Open the Source says Muslim growth “is largely driven by Muslims’ relatively young age structure and high fertility rate,” and it gives Muslims a total fertility rate of 3.1 children per woman in 2010–15, with Christians at 2.7.
• That page says about one in every 100 adults raised Muslim has left, and a similar number have switched in. For every 100 adults ages 18 to 54 raised Christian, the net loss was 11.6.
• Pew’s 2015 projection, built on 2010 data, has Muslims and Christians near parity in 2050 and equal in share around 2070, if current trends continue.

Which Religion Is the Fastest-Growing in the World?

Pew Research Center’s report, released 9 June 2025, covers 2010 to 2020. In that decade the Muslim count rose by 347 million. Pew says that gain was more than all other religions combined, and that the Muslim share of the world’s people moved up 1.8 points and stood at 25.6 percent. Christians stayed the largest group. Their numbers went from the previous count up by 122 million and reached 2.3 billion, while their share dropped 1.8 points and stood at 28.8 percent.

Is the Growth Births or Conversion?

Pew’s page on the factors behind the changeFactors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Muslim population growth is largely driven by Muslims’ relatively young age structure and high fertility rate.Factors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Open the Source says:

Muslim population growth is largely driven by Muslims’ relatively young age structure and high fertility rate.

Factors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025

The same pageFactors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Muslim population growth is largely driven by Muslims’ relatively young age structure and high fertility rate.Factors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Open the Source says Muslims had the highest total fertility rate in the study Pew used for 2010–15, an average of 3.1 children per woman. Christians were next, at 2.7. It also says Christians are shrinking as a share of the global population because of widespread switching out of religion, and that this disaffiliation overrides their demographic advantage. On switching itself, about one in every 100 adults raised Muslim has left the religion of childhood, and a similar number from another category have switched into Islam. For every 100 adults ages 18 to 54 who were raised Christian, Pew counts a net loss of 11.6 (17.1 left and 5.5 joined).

Pew addsFactors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Muslim population growth is largely driven by Muslims’ relatively young age structure and high fertility rate.Factors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Open the Source that the switching surveys “do not allow us to isolate the religious switching that took place exclusively between 2010 and 2020.” They describe patterns over recent decades. Pew also says the unaffiliated grew because of “large numbers of people – mostly Christians – switching into the ranks of the unaffiliated.”

The fair reading of Pew’s own sentencesFactors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Muslim population growth is largely driven by Muslims’ relatively young age structure and high fertility rate.Factors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Open the Source is that Islam’s faster growth in that decade was mostly children born to Muslim parents, while Christianity’s falling share was mostly people leaving religion altogether. It is not a report that large numbers of Christians became Muslims.

Is Islam Expected to Overtake Christianity?

The 2020 snapshot in the 2025 report still has more Christians than Muslims: 2.3 billion and 28.8 percent, beside a Muslim share of 25.6 percent. That report measures 2010 to 2020.

Pew’s forecast is an earlier report, The Future of World Religions, published 2 April 2015 from 2010 data. It projects “near parity between Muslims (2.8 billion, or 30% of the population) and Christians (2.9 billion, or 31%)” by 2050. Pew adds, “possibly for the first time in history.” If the model is extended, it says, the two shares “would equal” each other “at roughly 32% each, around 2070,” and by 2100 about 35 percent of the world would be Muslim and 34 percent Christian. Every one of those lines is conditional on current trends continuing, and Pew says the growth of both groups “would be driven largely by the continued expansion of Africa’s population.”

Appendix B of the 2025 report shows that region. In sub-Saharan Africa the population rose from 861 million in 2010 to about 1.12 billion in 2020. The Christian share went from 61.7 to 62.0 percent, and the Muslim share from 32.0 to 32.8 percent, so both communities grew with the region. In Asia-Pacific the Christian share fell from 6.1 to 5.9 percent, and the Muslim share rose from 24.8 to 26.1 percent.

Does a Larger Number Prove a Religion Is True?

Matthew 7:13–14Matthew 7:13 · King James VersionEnter ye in at the strait gate: for wide is the gate, and broad is the way, that leadeth to destruction, and many there be which go in thereat:Matthew 7:13 · King James VersionOpen the Source says the gate is wide and the way is broad that leads to destruction, and many go in there, and that the gate is strait and the way is narrow that leads to life, and few find it. Jesus is speaking about the road, not about a census. A faith can add hundreds of millions of children and still be false. A faith can lose share and still be true. The Christian confession is that Jesus is God, that he was crucified and raised, and that the one God is Father, Son, and Holy Spirit. Those claims are argued from the Gospels and from the Qur’an’s own words about him, on Jesus in the Qur’an and the Gospels and Is Jesus God?. Pew’s table does not adjudicate them.

The Qur’an has its own picture of growth. Surah 110, in Saheeh International, says, “When the victory of Allāh has come and the conquest, And you see the people entering into the religion of Allāh in multitudes,” and then, “exalt [Him] with praise of your Lord and ask forgiveness of Him.” The multitudes there come after a victory, and the answer the surah asks for is praise and repentance. It does not offer a head count as the proof of the message.

Frequently Asked Questions

Are More People Converting to Islam Than Leaving It?

Pew’s switching surveys, which cover recent decades rather than 2010 to 2020 alone, are nearly even for people raised Muslim: about one in every 100 has left, and a similar number has switched in. The large increase is births.

Which Group Gains Most From Switching?

The religiously unaffiliated. Pew’s factors pageFactors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Muslim population growth is largely driven by Muslims’ relatively young age structure and high fertility rate.Factors Driving Religious Change, 2010–2020 · Pew Research Center, 9 June 2025Open the Source says that for every 100 people ages 18 to 54 raised with no religion, 7.5 have left and 24.2 have joined, a net gain of 16.7. Buddhists show a net loss of 9.8 per 100 (22.1 left and 12.3 joined).

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