Global Religious Diversity Today

A report released last week from Pew Research Center, "Religious Diversity Around the World” (2026), provides a nice overview of religious diversity across 201 countries and territories. Using a modified version of the Herfindahl-Hirschman Index (HHI)—a measure economists typically use to assess market concentration—Pew constructs a Religious Diversity Index (RDI) ranging from 0 (complete religious homogeneity) to 10 (perfectly even distribution across seven religious categories).

The most religiously diverse country in the world is Singapore, with an RDI score of 9.3. No single religious tradition dominates: Buddhists (31%), religiously unaffiliated (20%), Christians (19%), Muslims (16%), Hindus (5%), and others (9%) all have significant presence. Suriname ranks second.

At the opposite end are Yemen and Afghanistan, where Muslims account for more than 99% of the population, yielding RDI scores close to 0.

A striking finding is that a single religious tradition forms a majority in 194 out of 201 countries. On the one hand, that makes it sound like religious pluralism is not quite so prevalent as might be supposed. Indeed, pluralism where no group exceeds 50% is rare, occurring in only seven countries. On the other hand, just looking at religious tradition can be misleading because there can be quite a lot of diversity in religious teaching and practices within a particular religious tradition. Just think of the Unitarian Universalists and the Amish, who both are rooted in Christianity (see the discussion on these groups in the book).

This last point is particularly relevant for the United States, whose RDI of 5.8 ties it with Nigeria as the most religiously diverse among the world's most populous countries. Although the U.S. is majority Christian (64%), nearly 30% are religiously unaffiliated, and smaller shares belong to other traditions. But keep in mind, too, that there is also tremendous diversity within Christianity in the United States, something that the RDI will not accurately account for.

The RDI is a good example of how a measurement concept that came from economics—namely the HHI—has found its way into the study of religion. However, you may be interested to know that the RDI is actually not the first time the HHI has been used to study religion, and it just takes a little internet sleuthing to find the earlier applications.

Overall, I suggest that you take away a two main lessons from this research report by Pew.

First, most of the world’s population lives in moderately diverse countries. Only 1% live in “very high” diversity contexts. This suggests that there are strong forces that drive both a degree of pluralism as well as a degree of concentration within a country. Can you think of some concepts from the book that would help to explain this fact?

Second, there is much to be gained by applying concepts from other disciplines to the study of religion. In this case, the RDI is an application of the HHI from economics, but of course there are many ideas that have come from sociology, psychology, and other fields. It is good to keep an open mind and an interdisciplinary view when studying religion.

Why Are There No Non-Christian Megachurches?

Megachurches—those congregations drawing 2,000 or more people each week—are almost entirely Christian, and usually Protestant, and it is natural to ask: "Why don’t we see megachurches in non-Christian religious traditions?"

At first glance, the pattern seems puzzling, especially because there are large gatherings in other religions traditions. For example, major mosques can host tens of thousands of persons for Friday prayers, and Hindu temples and Buddhist shrines attract massive crowds during festivals and pilgrimages. Yet, these gatherings do not resemble the megachurches as typically conceived by social scientist of religion: a single congregation, meeting weekly, under centralized leadership, offering a wide array of programs, and supported by voluntary attendance and donations.

From an economics-of-religion perspective, the explanation lies less in theology, which is where our attention might be instinctively drawn, and lies more in organization, incentives, and scale economies.

Let's first start with how religious “production” works. Christianity is unusually well suited to mass production. In a typical Christian congregation, the weekly gathering is sermon-centered with a preacher and an audience, and this setup scales efficiently. Once the fixed costs of buildings, technology, and staff are paid, adding more attendees is relatively cheap. That creates a potential incentive to grow large.

Contrast this with other kinds of religious activities that do not scale as easily. Small groups which focus on scriptural learning do not scale in the same way as a weekly religious service, and the building of strong social ties as in an Amish community also do not scale. Hinduism centers on household rituals and temple offerings rather than weekly congregational worship, so there is no scope for scaling up. Similarly, Buddhism often prioritizes meditation, monastic authority, and individualized practice. These modes of religious production generate fewer economies of scale, so there’s less payoff to building a single massive congregation.

Second, consider authority structures. Megachurches typically revolve around entrepreneurial leaders—charismatic pastors with significant autonomy over doctrine, programming, and branding. Indeed, about 40% of megachurches are non-denominational, which provides them with more flexibility in what they teach and how they operate. This governance structure works well in competitive religious markets like in the United States where religious groups compete with each other. In contrast, religions with strong centralized hierarchies (Catholicism, Shi’a Islam) or dispersed authority (many forms of Hinduism) limit the ability of any one local leader to grow a congregation unchecked.

Third, megachurches thrive in religious markets characterized by competition and choice. In the U.S., individuals can easily switch congregations, denominations, or opt out altogether. Under these conditions, growth-oriented groups can... well... grow! And growth-oriented groups, especially evangelical Christian groups, are also internally motivated to adapt their style of religion to appeal to segments of the population who are dissatisfied with other options. Other traditions, especially those tied to ethnicity, family, or inherited identity, face weaker incentives to compete for marginal attendees.

Thus, the absence of non-Christian megachurches is about the underlying economics of religious production, authority, and competition, and that also means that megachurches in other religious traditions are possible. It is really a question of whether the congregation's leaders prioritize growth and are willing to design religious services in a way to accommodate that growth, and whether there is demand for it by religious consumers. Remember, there's a supply side and a demand side. As proof of this concept, there are in fact some large, non-Christian congregations. One example is Temple Emanu-El in New York, which is reported (though I cannot confirm) to have over 2000 families in its membership.

The megachurch is ultimately an institutional solution that some congregations have adopted, and although Christian congregations are well-suited to this solution, Christianity is not the only religious tradition that can leverage this institutional arrangement.

Acknowledgement: ChatGPT 5 assisted in the writing of this post.