The Future of Faith: Is the World Becoming More or Less Religious?

For decades, we've heard competing stories about religion's future. 

Some point to declining religious participation in parts of Europe and North America. Others point to the growth of religious communities across Africa, Asia, and Latin America. At the same time, increasing religious diversity is changing the religious landscape in many countries around the world. 

So what should we make of these trends? And what do they tell us about the future of religion? 

I’m Jonathan Beasley, and this is the Harvard Religion Beat. Today, I'm joined by Gina Zurlo, Lecturer on World Christianity at Harvard Divinity School. A historian and sociologist of world Christianity, Zurlo studies global religious change, migration, demographics, and the shifting religious landscape around the world. 

Together, we'll explore what the latest research reveals about the future of religion—and why one of the biggest unanswered questions may be what comes next for Gen Z.  

Jonathan Beasley: Gina Zurlo, thank you for joining me today. When you zoom out and look at religion globally today, what are the biggest trends that stand out to you?  

Gina Zurlo: So Christianity is still the world's largest religion for now. That may change by the end of this century. Current projections show that probably by the year 2100, Islam will be the world's largest religion. And that's mostly because of birth rates. On average, Muslims have 3.1 children per woman whereas Christians have 2.8. So just looking at math, that's where it will go if all things remain the same. But as Christianity, the world's largest religion, it is also demographically shifting to the Global South. So there are more Christians in Asia, Africa, Latin America, and Oceania compared to Europe and North America.  

Jonathan Beasley: You've written extensively about Christianity's shift toward the Global South. What's most important for listeners to understand about that shift?  

Gina Zurlo: There's a lot of tensions in this shift, actually, and this is a major theme that I've been teasing out in this work of, what does it mean that Christianity is now majority Global South? So if the demography has shifted, have other aspects of Christianity shifted? Has theological education shifted? Has theological consciousness shifted? Has the money, the economics of Christianity shifted? Has historical consciousness shifted? And more often than not, the answer to those questions are no.  

So we've got this tension where most of the people of Christianity are in the South, but a lot of the resources are still in the North. A lot of the money is still in the North. The way theology is conceptualized, the history that we read about church history is still primarily Northern. So we need to make a lot of adjustments in order to really represent what Christianity looks like now.  

Jonathan Beasley: Why haven't the resources reached the Global South? And how does that shift happen then? 

Gina Zurlo: So a lot of its money, frankly. And I think we need a lot more economic analyzes of world Christianity, because a lot of the places where Christianity has shifted to in the twentieth century generally are lower socioeconomic status places. Generally, they are less healthy places. They have fewer resources. And so we still have these powerhouses in the West, the United States in particular, which has a huge role, outsized role, frankly in all of these trends that I'm mentioning, in mission, in money, in theological education, in media. So I think this is just going to take a long time to see these other aspects of Christianity shifting along with the demography. 

Jonathan Beasley: There are about 2.6 billion Christians worldwide. That figure contains or maybe hides a lot of internal diversity. How should we be thinking about what global Christianity, world Christianity actually means today?  

Gina Zurlo: Yeah, I think a lot of Americans in particular—actually, this is not just an American problem. A lot of people generally are pretty myopic about faith. When they hear there's 2.6 billion Christians, everyone just kind assumes everyone is like them. And that is the furthest from the truth. This is a hugely diverse religion. All different languages, ethnicities, political situations, histories, I mean, cultures, it's hugely diverse. And I think a lot of people are not quite aware of the huge diversity that exists within world Christianity. And that too creates a lot of tension, especially thinking, for example, theologically.  

So you might have your own particular theological convictions, and that's fine. But there are lots of Christians in the world who may not hold those particular theological convictions, but they still call themselves Christians and are still just as committed to their faith as you are. And so how do you reconcile that in your own mind? If you've got Christians who maybe aren't Trinitarian, is that orthodox to you? Is it heterodox? What does it mean that you both call yourselves Christian? One is Trinitarian, one is non-Trinitarian.  

Jonathan Beasley: Let's turn to the Pew Research Center's report on religious diversity from earlier in 2026. What were the headline findings that stood out to you?  

Gina Zurlo: Yeah, it's kind of a mixed set of findings in the report. So if you look at the twentieth century, actually a lot of places got less religiously diverse, say, Sub-Saharan Africa, as people from African traditional religions converted to Islam or Christianity. So we had fewer religions happening in Sub-Saharan Africa. A lot of the trends are still the same where you have a majority religion. A large proportion of the countries in the Pew report still had a Christian majority, even if that Christian majority is declining.  

So at a global level, it might be kind of hard to see the change. Again, it's the local level, I think, where the change is most perceived. In a place like the U.S., where you might have a Hindu temple or a Buddhist temple where you never had one before. Like in the Midwest, a lot of people are noticing, oh, my gosh, there's temples here in the Midwest that were never here before. So I think you're seeing a lot of different trends come out in terms of religious diversity.  

Jonathan Beasley: So the U.S. shows up as really diverse among the largest countries, the most religiously diverse country, I believe, with the top 10 population, but it's not the most religiously diverse globally. Does that shift how we should be thinking about religion in the US, or, like you said, I mean, we have Hindu temples, Muslim mosques, we have all these different representation of the diversity that we're seeing across the religious landscape. How are you thinking about this? What does this mean to you?  

Gina Zurlo: Yeah, so I hear a lot of people say, oh, the U.S. is the most religiously diverse country in the world. That has never been true. That's not true. It is in terms of large countries. But Singapore and South Korea have way higher rates of religious diversity than the US does. And the thing that is most interesting to me about the religious diversity discussion in the US is religious diversity in the US is new looking at the long scope of history. It's only since immigration change in 1965 that we now have larger populations of Muslims, Hindus, Buddhists and other religions coming into this country.  

So in terms of how to respond to religious diversity or what it means to live among people of other faiths, we ought to be reading Singaporean theologians and commentators, we should be reading Korean theologians and commentators, people who have always lived in religiously diverse contexts. And I think this has been a problem for a lot of Americans who think we invented religious diversity, when really Asian people of faith have been always living in religious diversity and have a much better idea about how to do that.  

So that's where this global Christianity perspective can really help us by giving us that big picture of, oh, my gosh, religious diversity is just the norm in East Asia. Maybe there's something there we as Americans can be learning from.  

Jonathan Beasley: You're listening to Harvard Religion Beat from Harvard Divinity School. 

Before we get back to my conversation with Gina Zurlo, if you'd like to go deeper into today's conversation, she recently explored many of these themes in the new Harvard Divinity Bulletin essay titled "Is the World Becoming More or Less Religious? Depends on China." You can find that essay, along with the Pew Research Center report we’ve discussed, in our show notes.  

And if you’re interested in more conversations like this one, you can find more from Harvard Divinity School through our newsletter and on social media. You can find links to each of these opportunities in the show notes. 

Now, let’s get back to my conversation with Gina Zurlo.  

Jonathan Beasley: When demographers look at the future of religion, what are the biggest forces driving change?  

Gina Zurlo: Yeah. So there's only three ways a religion can grow at the national level. You're born into it convert into it, or you move into that country with your religion. There's only three ways a religion can decline. You die, you leave it, or you leave your country with your religion. So this is what we call the six dynamics of religious change. So thinking of the future of Christianity, and of all religions, frankly, the major driver is birth rates. That's the thing that most demographers of religion are looking at right now.  

And really, the Pew Research Center has done some of the best work in figuring out the differential birth rates by religion that I mentioned earlier, where Muslims have the highest and Buddhists actually have the lowest. And so frankly, from a math perspective, we can project out the different growths of each religion in each country using United Nations population projections and using the birth rate data to see what the future may be.  

In terms of switching or conversion, this is probably one of the hardest ones to figure out. Under what conditions do people switch religions? That's a very difficult thing to discern because there's a lot of external factors that play into that. If there's a natural disaster, we tend to see spikes in religiosity. There have been mass conversion movements to Christianity in the 20th century and prior. Could that happen again? Maybe, maybe not. We've seen people switch from Catholicism to Orthodoxy in mass, but again, these are really hard to predict.  

And then migration, the third piece, of course, is a net zero globally, because where you move from one place leave from another, but has a huge impact at the local level, where we're seeing massive populations of migrant Christians in every major, say, European city. So in Italy alone, there's at least 1,000 congregations of Nigerian and Ghanaian Pentecostals, just in Italy. And they have a lot of problems being considered, quote, "real Christians" in this Catholic majority country. So migration is having a huge impact at the local level.  

Jonathan Beasley: One thing that surprised me was your point that immigration alone isn't enough to offset declines in religious participation in some countries. Can you explain that?  

Gina Zurlo: Generally, people leaving churches is happening at a faster rate than those who are entering a country. So immigration is not really making up for the, quote, "losses." Now, the United States is an interesting case of this, because the United States is currently the country with the most Christians in the world, yet has been experiencing a decline in its Christian population. Well, how can both of these things be true? So for a long time, the answer was immigration from Latin America. So people coming across the Southern border has been the thing that has kept the United States as the country with the most Christians.  

But now the border is closed. So the current immigration policy will have a definitive impact on the demographic future of Christianity in the United States. And those at most at risk for deportation under the current administration are majority Christian, 80 percent Christian. So it seems rather counterintuitive, frankly, that Christians are the ones getting deported and the ones being not able to move into the country. But it will mean by 2075, the United States will drop to the third country with the most Christians after the Democratic Republic of the Congo and Nigeria. That's a very different kind of world Christianity than we know today.  

Jonathan Beasley: You drew a distinction between institutional religion and spirituality. Why is that distinction so important when we're talking about younger generations?  

Gina Zurlo: We know there are trends by generations. You can see, the Boomer generation to Gen X, Millennial, Gen Z, there's a definite trend away from institutional religiosity. Now the big question, though, is there a trend away from spirituality? And this is the crux. This is a really big question in the social scientific study of religion right now. Is it institutional religion that's declining? Yes.  

But is it spirituality that's declining? Maybe not. Maybe Gen Z has a more creative, more individualistic, not sure, approach. Maybe they have different ways of conceptualizing what it means to be religious in the world that's not attached to the institution. So the data is still, in my opinion, a little fuzzy on it. We are seeing this trend away institutionally, but I'm not 100 percent convinced that they're all just giving it up altogether and they're totally secular. I'm not sure the data supports that either.  

Jonathan Beasley: I mean, certainly at a place like HDS, we hear about the spiritual but not religious crowd, which makes up not a majority, obviously, here, but a significant part of the population. I'm curious just about going into the classroom with the courses that you're teaching, what are the kinds of conversations you're having with the students, and in particular, what kinds of questions are they raising? What are you seeing in those conversations with your students?  

Gina Zurlo: Yeah, so most of my students are Gen Z, and they too are asking me, what's happening with Gen Z? And I'm asking them, what's happening with your generation? So no one really knows to be honest, I don't think we have enough studies yet to really-- because also, these are younger people. And so it takes time to get that longitude. We don't have any longitudinal data about Gen Z yet because they weren't old enough to survey them 10 years ago. So I think over the next 10 years, we'll get a better sense. And I know that might sound really unsatisfying to people, that it's going to take a decade to figure out what's happening. But there is a lag time in demography.  

Demographers are not the best people to ask about what's happening right here, right now because we need time for the data to settle in before we can really what changes have happened. Now, the survey methodology people and the people who do surveys, they have their finger on the pulse a little bit better about current trends, but I'm waiting to see a little bit more survey data before I make my final decision on what Gen Z is up to.  

Jonathan Beasley: Do you have idea? Are you thinking in one particular area?  

Gina Zurlo: I do think institutional religiosity, definitely on the decline. All the data seems to point in that direction. But I do think there is some kind of creative spirituality happening. But again, I'd like to see some more data on it.  

But I'm open to the fact that Gen Z has a different way of thinking about religiosity. And if we're not asking the questions in a way that makes sense to them, what kind of data are we really getting? So let's get the 21-year-old and the 22-year-olds in the room to ask questions in a way that makes more sense to their generation. I think we might be surprised by what we find.  

Jonathan Beasley: Gina Zurlo, thank you for your time. Questions about religion's future often get framed in simple terms: Is religion growing or declining? Are younger generations becoming more religious or less religious? 

As Gina Zurlo's research suggests, the reality is far more complex. 

The story of religion today is also a story of demographic change, migration, religious diversity, and the different ways people understand faith and belonging around the world. And as those patterns continue to evolve, so too will our understanding of what religion looks like in the twenty-first century. 

The Harvard Religion Beat is presented by the Office of Communications at Harvard Divinity School. It is produced and hosted by me, Jonathan Beasley, and it is edited by Tyler Sprouse.   

Thank you for listening. Until next time...