Is Islam Really the Fastest-Growing Religion?

This question led me down a rabbit hole.

After the assassination of Charlie Kirk this year, it felt like a lot of people were suddenly talking about God, church, faith, repentance, and America “getting back to its Christian roots.” I kept seeing posts about revival, full churches, bible sales being at an all time high and people turning to Christ in their grief and fear.

At the very same time, I was hearing on various podcasts and social accounts that Islam is actually the fastest-growing religion in the world and maybe in the U.S. too. That left me wondering:

• Is there really a Christian “comeback” happening?

• Is Islam actually the fastest-growing religion?

• And what in the world is actually happening in the United States?

So I went looking for hard data. Let me tell you what I found…

1. Globally: Islam is the fastest-growing major religion

According to demographic research (especially Pew):

• Islam grew 21% from 2010 to 2020, the fastest of any major religion.

• This growth is not primarily from conversion.

• It is mainly from:

  • Higher birth rates

  • Younger population age

Muslim-majority nations tend to have more children per family, and the population as a whole is younger; meaning more people entering child-bearing years.

That’s why Islam grows quickly on a global scale.

And yes, this includes counting children. But every religion’s demographic numbers include children, because children shape the future of that religion. Kids born into a faith community are raised in its beliefs, and many remain in that identity as adults. That’s why demographers track births.

Globally, the second-fastest-growing category isn’t another religion at all; it’s the religiously unaffiliated (“Nones”). They’re now the third-largest “belief group” in the world.

2. In the U.S.: the fastest-growing “faith” is actually losing your faith

This part honestly grieved me.

In the United States, the fastest-growing category isn’t Christianity, Islam, Judaism, or any other world religion.

It’s the religiously unaffiliated — the “Nones.”

This group is exploding in size:

• Roughly 28–29% of Americans now identify as non-religious.

• It grows every single year.

• Young adults are leaving religion at the highest rate in American history.

This should concern all Christians, not because of cultural power, but because we know it grieves the heart of God when people walk away from Him.

3. So what is the second-fastest-growing religion in the U.S.?

This was the confusing part, because the answer honestly depends on how you measure growth.

To keep things crystal clear, here are the two ways researchers do it:

A. Counting births + immigration (standard demographic measurement)

The second-fastest-growing RELIGION in the U.S. is: Islam.

Why?

• Muslim families have slightly higher birth rates

• Immigration brings more Muslims into the U.S.

• Conversion into Islam is steady but not massive

• Conversion out of Islam roughly balances conversion in

So demographically, Islam shows as #2, not because of huge conversion waves, but because of birth rates + immigration.

This is the same reason Islam grows globally.

And this method matters because birth rates shape the next generation.

B. Measuring only adult religious switching (what people choose)

If you completely REMOVE births and only count adults converting, the answer changes completely.

➡️ The second-fastest-growing faith community by ADULT CHOICE is:

Non-denominational Evangelical Christianity.

These churches gain:

• The most adult converts

• The most people leaving other Christian denominations

• Many who were unaffiliated but return to Christianity

Even though American Christianity overall still loses more people than it gains, within Christianity, non-denominational churches grow the most through actual adult conversion.

So:

• With births included → Islam is #2

• With births excluded → Non-denominational Christianity is #2

• And overall, the “Nones” are #1 by a landslide

That’s the cleanest, most accurate way to explain it.

4. WHY are so many Americans leaving religion???

Researchers point to several major themes:

• Christianity feels too political

Many can’t distinguish between following Jesus and aligning with a political party and they want no part of that.

• Institutional distrust

Scandals, abuse, hypocrisy, and cover-ups have profoundly damaged trust.

• Radical individualism

Our culture disciples people to follow “my truth,” not God’s truth.

• Perceived conflict with science or modern life

Often a misunderstanding, but perceptions still push people away.

• Shallow formation

Many grew up in church culture but were never discipled, so their faith didn’t have roots.

• Digital life + overload

People are overwhelmed and disconnected from real community.

• Church hurt

Not theological but personal. And I understand this one deeply.

I’m not speaking from a distance.

I have personally experienced church hurt, especially in certain Protestant spaces. It left me stepping back, re-evaluating, and honestly feeling spiritually disoriented for a season.

That’s part of why I’m re-exploring my Catholic roots and beginning to look into Orthodoxy. At this stage of my life, I’m craving:

• Tradition

• Reverence

• Beauty

• History

• Stability

Something rooted. Something ancient. Something deeper than modern church “culture”.

Additionally, I fully understand why Christian nationalism turns people off

I’ll be honest: I sometimes almost cringe saying I’m a Christian. NOT because I’m ashamed of Christ, but because I don’t want people to assume I’m part of Christian nationalism.

I’m NOT a Christian nationalist, and I often feel the need to explain that so people know “what kind” of Christian I am.

Christian nationalism is absolutely one of the factors pushing people away from religion in this country, especially young adults. And it’s harming the witness of the church.

But it isn’t the only reason people leave. It’s one piece of a much bigger picture.

• Globally:

  • Islam is the fastest-growing major religion (mostly because of birth rates).

  • The “Nones” are also growing rapidly.

  
  

• In the U.S.:

  • The fastest-growing “faith” is losing faith — the unaffiliated.

  • The second-fastest-growing religion is Islam if counting births and immigration.

  • The second-fastest-growing faith community by adult conversion is non-denominational Christianity.

When people walk away from God, it grieves Him; which means it should move us to compassion, prayer, and reflection.

Christianity has a long, beautiful, historical foundation worth discovering or rediscovering. We need to separate Jesus from the noise of modern politics and the church needs healing, humility, and authenticity now more than ever.

Trends will shift. Culture will change. But Christ remains steady. Let’s bet he kinds of Christian’s that reflect the characteristics of Christ and not the exact opposite of that.