[Link] One in five American adults say they are atheist, agnostic or "nothing in particular"

Thanks for the feedback. I wondered whether I should post a link to the Pew study. I decided in favor of it because I assumed that news about changes in religious belief over time would be of interest to rationalists, but if others agree that articles of this sort do not belong here I'd be happy to remove it. Thanks again.

I don't think this topic is a mindkiller. Atheism isn't a guarantor of good reasoning, especially as the number of atheists grow, and you end up with more people raised atheist who haven't necessarily had experience with actually changing their mind. The demographic expansion points to the weakening power of atheism to signal the correct contrarian circle.

If we're going to become a subreddit, can we become r/nongolfers?

Isn't America also more religious than other developed countries across the world? Regardless, a comparison would be welcome, if the article were posted at all.

I think one of the older studies delved into the demographics of individuals switching between faiths in detail.

Some of what you're seeing instead is that the youngest cohort is the least protestant, while the oldest is the most. Project that out 5 years with new young people and a loss of older people, and just constant percentages in each cohort makes a dent, though I'd guess that there must be some switching as well, for such a large jump in the whole population.

Catholic membership across cohorts is relatively constant, so it doesn't show that effect, but white catholics are disappearing, while hispanic catholics grow to keep the overall numbers constant. So white catholics are likely leaving too.

At least judging from my model of American Protestants (which is mainly based on stereotypes, and hence likely to be inaccurate), Catholics say more reasonable things than Protestants (e.g. few Catholics deny evolution anymore), so the amount of compartmentalisation needed to stay a Catholic while supporting the mainstays of modern science is smaller than that needed to stay a Protestant.

Or Catholics are becoming atheists and Protestants are converting to Catholicism. (Other possible explanations involving birth rates and immigration have been mentioned in other subcomments.)

The percent of Catholics has been steady for the past 40 years, but the study says this is because they are replenished by hispanic immigrants. But the percent has been steady for the past 5 years as well, despite net zero hispanic (mexican?) immigration. I didn't notice if the study directly answered your question. Also, 1/3 of US hispanics are protestant, so that's one form of leaving Catholicism.

Also, much of the effect is people leaving the religion of their parents that they never identified as, so, as fortyeridania says, relative fertility is relevant. But I don't think there's much of that in the US these days.

I haven't looked at the study.

However, the graph presented by no means entails that Protestants are becoming atheists more than Catholics are. In fact, it could be that Catholics are significantly more likely to turn atheist than Protestants are.

Suppose Catholics have many more children than Protestants. If those Catholic children are more likely to eventualy become atheists than Protestants are, it could produce a graph such as the one shown--a flat line for Catholicism (which experiences strong positive and negative changes, from the kids and deconversions), and a rising line for atheism.

As for Protestantism, even if the decrease is explained totally by flights to atheism, the magnitude of Catholic apostasy could just outstrip that of Protestant apostasy. As long as Catholic fertility matches Catholic apostasy, the graph will not change.

The increases for unaffiliated are most pronounced in the youngest

No, increase in unaffiliated is the same 3 points for older millenials, gen X, and boomers, with no change in older people. It is much less pronounced in any cohort than in the population as a whole. Younger millenials are not "up to 34%," but have only been measured once, at 34%.

Over the past 5 years, half of the effect is due to "young" people, including boomers, becoming less affiliated, but the other half is a cohort effect as old people dying off and are replaced by young people with a much lower rate of affiliation.

The original post already included a link to the online study ("executive summary"), but thanks anyway.