“The Future of Religion” is one of those big picture questions that has been addressed by a wide variety of intellectuals such as Freud, Rorty, and basically every European intellectual in the 19th century. (The fact that the end of religion has been right around the corner for more than a century now doesn’t help one’s confidence in predictions of its demise).
While grand narrative, direction-of-history discussions are fun, they should not take the place of more rigorous data-driven estimates when such are available. (Incidentally, this happened with the Democratic Party in the US when they strongly relied on a demographically naive “direction of history” narrative to assume they would effortless dominate US politics in the future without, you know, actually talking to a political demographer, but I digress.)
In the past two decades some demographers have started to project religious groups like they would project the population of a country. Projections rely on three forces: births, deaths, and migration, projections of religions just switch out migrations for conversion to or away from “religious switching.”
Unfortunately, Latter-day Saints are too small to really do a demographic projection for without the Church’s in-house data, but there have been various insightful projections for major world religions by Pew as well as other researchers. While there are a lot of assumptions that are baked into these projections, they’re the most rigorous that we have.
To summarize: while many people leave religion, the fact that secular people have hardly any children means the share of the non-religious will shrink worldwide over the next couple of decades, although the secular share will probably increase in some pockets like the US, but even there the best estimate is that the percent secular will peak and then start to decline.
On the other hand, religiosity is connected to economic development, and if technology progresses to a degree that we see worldwide economic development (hopefully!), that may lead to a decline in religiosity globally, but that’s hard to predict.
So what does this mean for the Church? As I’ve mentioned before, the Church is declining in places that are declining, and growing in places that are growing. In terms of fundamentals for growth it doesn’t get any more solid than that. However, the background society for the Church’s center in the US will continue to become more secular, so for us US members it will look like all those intellectuals were right about the future of religion as it becomes less and less relevant in society. However, that is a very short-term, localized view.
According to these projections by 2050 Islam will be about the same size as Christianity, and in many Islamic contexts proselytizing a Christian faith is taboo, to put it gently, so the expansion of faith in some contexts may not help the Church’s growth. Once again, the big story here is Africa. By 2050 4 out of 10 Christians will be in Africa. As a potential missionary field Sub-Saharan Africa will probably continue to explode population-wise (although how long their population will continue to explode is a matter of fierce debate in the demography community).
Finally, taking a more big picture, long future approach, from twin studies we know that religiosity is at least somewhat genetic, as are one’s desires to have children. Consequently, inasmuch as religiosity is at least partially biologically engrained, in this world of widespread contraception it’s possible that we may actually evolve as a species towards religion (a paper I published looked at some of the speculative math behind evolving towards higher fertility), but of course this is very speculative.
So to summarize, religion is not dying, even if it might look like it in certain cafes and cities.