Conrad Hackett is associate director of research and senior demographer at Pew Research Center and a contributing author to an academic paper written by an international team of scholars that explores the three stages of religious decline. A few weeks after its publication, Hackett penned a Pew Research article that summarizes the paper.
While variations of secularization theories have long explained the decline of religious identity in Western Christian nations, this work suggests the global decline in religious identity applies universally. More specifically, the authors explain:
“We propose that secularization follows a consistent sequence: first, participation in public rituals declines; second, importance of religion drops, and third, people shed their formal belonging. We refer to this as the Participation–Importance–Belonging (P-I-B) sequence. This ordering reflects the relative costliness of each behavior: public ritual attendance demands the most time and energy, while mere identity affiliation is least burdensome and thus most persistent. The P-I-B sequence normally does not occur within the lifespan of an individual but rather transpires across extended periods among cohort groups.”
Importantly, their findings support this thesis. The only group of countries that doesn’t follow the model as expected are eastern, post-communist countries. Here the authors suggest that events in recent decades have caused a temporary “nationalist-religious upswing” that has masked the underlying longer-range secular shift.
So What
It is very clear that religious identity has been declining in the United States and other primarily Christian nations for some time. In fact, Hackett reminds readers of a different Pew Research Study that explored changes in religious group affiliation between 2010 and 2020. It showed that “the share of the population that was affiliated with any religion dropped at least 5 percentage points in 35 countries” while the decline was more dramatic in places like the United States, which experienced a decline of 13%.
The research shows that secularization is happening far beyond the Western Christian world. This has important implications for how we understand that trend and for the role of religion in each country in the present and what is likely in the future, depending on where it falls within the PIB sequence.
Note: Full article referenced is Stolz, J., de Graaf, N.D., Hackett, C. et al. The three stages of religious decline around the world. Nat Commun 16, 7202 (2025). https://doi.org/10.1038/s41467-025-62452-z