It's no secret that of all Western countries, the US has retained the highest level of religiosity in modern times. Today I figured out why. It has surprisingly little to do with Americans being inherently more receptive to religious messages, and more to do with the manner in which America changes religion.
In Europe, before Martin Luther, there were Catholic Churches. And then there was the Protestant Reformation. Or should I say, the Magisterial Reformation, because in practice the big Protestant sects merely replaced Catholicism as the state religion. With that came a high degree of uniformity. Lutheran churches looked alike, worshiped alike, prayed alike, and sermonized alike. There was no "religious marketplace", because these conditions made for a monopoly.
Since religion, outside of compulsory attendance, is an optional good that one might choose not to engage with, one might compare it to eating out. If the only option you have for eating out is one mediocre hamburger joint, odds are you'll cook for yourself more and eat out less, if at all. But if you're surrounded by tasty restaurants? Well, that's a different story.
Since the 19th century, religion in the US has been less of a monopoly and more like a marketplace. Does your town have a single church whose pastor bores you to tears? Well, one day a traveling Methodist tent preacher shows up in your area. His style of religion is different. His message hits home different. You happen to find it more compelling. So you have a conversion experience.
With time, of course, the range of options expanded dramatically. At least if you live in the Bible Belt, one can "church shop" with unprecedented ease. This fosters a very competitive environment between churches. Anyone can call themselves a pastor, which means anyone can try to one-up the neighboring church by offering a product that draws in the most people. If you're dull and nobody likes your church, you'll go belly up and somebody else will take your place.
America, in short, is a laboratory that produces excellent churches, or at least if we measure it by mass appeal. And it's not "just" conventional churches either. There are parachurch organizations; for example, religious radio or publishing houses which put out religious literature with lucrative sales in mind. A pastor named Rick Warren, taking a page from the self-help industry, wrote a book titled The Purpose Driven Life, which to date has sold more than 50 million copies.
The most competitive churches skew Evangelical (loosely speaking, "non-denominational"). That's because, not being tied to a well-defined church model, they are comparably freestyle and you see a lot more variation between them as opposed to, say, a random two Methodist churches.
In 1990, a Pizza Hut opened in the Soviet Union, and this was a big frigging deal within the country. Everyone wanted to eat there when it first opened. Decades of competition in the fast food industry produced one of the greatest American restaurant chains. When it arrived on the shores of a country where everyone was eating government-issued cans of borscht, slices of pizza sold like hot cakes.
By now I think you can guess where I'm going with this. American churches aren't limited to America; instead, they routinely try to proselytize overseas and plant churches in their own image in foreign countries. Assuming that local regimes don't curtail their freedom to operate (e.g. in Russia), American churches fine-tuned to efficiently draw crowds will brush up against longstanding local monopolies that've never had to earn their keep, or so to say. And it's just like taking candy from a baby.
Whereas the old Protestant churches struggled to penetrate the Catholic landscape of Latin America, about 31 percent of all Brazilians were Evangelical in 2020. One source projects that the number of Evangelicals will be nearly on par with the number of Catholics in 2032, and after that they may become the largest religious group in the country. Brazil, of course, is not the only Latin American state undergoing this demographic shift.
In the Philippines, Evangelicals went from 2.8% of the population in 2000 to 14% in 2017. In Ethiopia, an Oriental Orthodox country (the most historically insular of all Christian branches), nearly 23% of the population is P'ent'ay (lit. "Pentecostal", but now a catch-all term for Evangelicals).
In Europe, it was reported c. 2022 that a new church is planted in France every 10 days. Assuming the average congregation has 200 members, that corresponds to about 7,200 new converts every year. This pace has been ongoing since at least 2017, and presumably continues today.
What I'm describing is a seismic shift in global Christianity. It is evangelical-izing, which is a cultural export of the United States. Forget Coca-Cola and Hollywood; America is enough of a soft superpower that in another 20 years the world's largest religion will have comprehensively and irreversibly changed. The new church is less traditional, less doctrinally focused, more experiential, aesthetically modern, more media-driven, and more organizationally fragmented, with each being an island unto itself.