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For years, religious leaders in the U.S. have raised concerns about the rise of the “nones” - people who profess to adhere to no faith tradition. 

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Among American adults under 30, “none” significantly outranks Protestants and Catholics as a religious affiliation.

There’s a certain conventional wisdom that young people often fall away from the Church for a time, but return as they become older. 

But the data suggests otherwise. 

Large continuing surveys like the General Social Survey (GSS) - which has asked samples of Americans questions about their lives and beliefs since 1972 - show that each recent generation has a fairly stable level of religious belief and practice after reaching adulthood. 

Younger generations of Americans are simply less religious than their parents and grandparents - and significantly so.

What does that mean for evangelization? When it comes to retaining members, how do Catholics compare to Protestants? 

And what can Catholic leaders learn from statistics about the future of the Church?

The Pillar took a look at the numbers.

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To see what the pews may look like in 20 or 40 years, The Pillar looked at the GSS-reported religious affiliations of younger adults — ages 18-30— at 20-year intervals.

The results are startling. 

In the surveys conducted from 1978-1982, 57% of young adult respondents to the GSS described themselves as Protestant, 27% said they were Catholic, and 13% described their religious affiliation as “none.”

A generation later, among those who were young adults in 1998-2002, the number of “nones” had climbed to 22%, while Protestants declined to 44% and Catholics to 25%.

But it’s the current generation that has seen the greatest change. Among young adult respondents in 2018-2022, 42% described their religious affiliation as “none,” 29% as Protestant and 19% as Catholic.

Compared to their grandparents’ generation, the number of Protestants has dropped by half, those describing themselves as Catholics have decreased by 30%, and the number who have no religious affiliation has more than tripled to become the largest group.

 Drastic Protestant decline

While Protestants saw a drastic drop in U.S. membership over three generations, the decline in affiliation is not even across different Protestant faith traditions.

The group of Protestant communities sometimes called “Mainline Protestants” has seen most of the decline. In this data, the group consists of Episcopalians, Lutherans, Presbyterians, and Methodists, though there are other communities not listed in the GSS data which are also considered mainline.

Nineteen percent of young adult respondents described themselves as belonging to one of the mainline denominations in 1978-1982, but by 2018-2022 only 5% of young adults belonged to one of these communities.

The group labeled as “Other Protestants” includes more evangelical denominations, including the various denominations of Baptists, the Missouri Synod Lutherans, and the African Methodist Episcopal communities, as well as non-denominational Protestants.

These evangelical and non-denominational Protestants decreased from 38% of young respondents in 1978-1982 to 24% in 2018-2022. This is still a very significant decline, but not as large as among mainline Protestants.

Looking at the specific denominations tells an even more dramatic story.

The number of young adult respondents claiming membership in every single named Protestant denomination had declined by 65% or more over the last 40 years. Baptists had declined the least, at 65%, while Lutherans had seen the largest decline at 75%. But across the board this was a change which can only be described as a collapse.

Meanwhile, non-denominational and other Protestants had actually seen their share increase slightly among young people.

The change was so dramatic that it created a question about data quality. Did younger respondents simply not know the denominational affiliations of their churches anymore?

But the answers from respondents ages 31-45 showed a similar trend.


Short of some dramatic reversal in these trends, in another 30 years fewer than 12% of all Americans will belong to one of the historic Protestant denominations. 

This may provide a sobering data point to those who have argued that in order to be relevant to younger generations, the Catholic Church must follow the example of mainline Protestant communities in ordaining women clergy and adopting same-sex marriage. Despite these communities having adopted these supposedly popular practices, younger generations have already abandoned them.

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Conversion, reproduction, immigration

So why has a dramatic change occurred among American Protestants?

Demographic data such as this is unable to answer many of the most important religious and human questions. The General Social Survey is not able to tell us about people’s religious conversions or their personal relationship with Christ.

One thing that the data can shine a light on is where people who have changed their religious affiliation from that of their upbringing have gone. The results here are fairly stark.

Only 54% of young adult respondents in the GSS during 2018-2022 who were raised Catholic still consider themselves Catholic.

However, that 54% retention rate is higher than for any denomination of Protestants.

At the very lowest end of the retention spectrum, only a third of respondents raised Episcopalian still consider themselves Episcopalians, while two-thirds describe themselves as having no religion.

Non-denominational and other Protestants have retained their share of the population because they attract more converts than any other Christian religious group, not because those brought up in that community have remained within it. Only 51% of those who grew up as non-denominational or other Protestants still consider that their affiliation.

But while non-denominational and other Protestants have more converts than any other Christian group, the religious group which has both by far the highest retention rate and the highest conversions from every other faith tradition is “none.”

Nearly 80% of young adults who grew up with no religion still have no religion. Added to their ranks are about a third of respondents raised in every Christian community, Catholic and Protestant.

While conversion and retention are clearly the most direct factors in the changing religious landscape, another possible factor is differences in reproduction. Is the shrinking share of mainline Protestant denominations as compared to nones and Catholics partly a result of having fewer children?

The Pillar looked at GSS respondents from 2018-2022 ages 48-60, the generation who are the parents of the young adults ages 18-30.

None of the trends here were dramatic, but several numbers did draw attention. Those with no religion had fewer children than any other religious affiliation except Episcopalians. This means that if those with no religion had as many children as religious Americans, the share of nones in the younger generation would actually be even larger than it is.

Catholics as a whole did not have more children than mainline Protestants; however, there was a significant difference between the number of children in Catholic families which go to Mass at least once a week as compared to Catholics who attend Mass less frequently. 

Since other surveys have suggested that Catholics raised in families that go to Mass regularly are more likely to continue to identify as Catholic than those who are not taken to Mass as children, the larger families of Mass-attending Catholics might be one explanation for why Catholic affiliation has not shrunk as fast as other Christian communities.

But there is another factor which many will naturally ask about: immigration.

The growing presence of Hispanic, African, and Asian members in the Catholic Church is a phenomenon shared by many non-denominational Protestant churches as well. 

What do trends in religious affiliation look like if Hispanics and immigrants are excluded?

 With those young Americans excluded from the data, the increase in the number of non-denominational Protestants and those with no religious affiliation is even greater, as is the increase in those describing their faith as “other.”

Protestant denominations still decrease by 60% or more over the last two generations. And the decrease in the Catholic population is more pronounced, though at 50%, still less than that of any Protestant denomination.

It’s also worth noting: if Hispanics and immigrants were excluded from the data, non-denominational Protestants would significantly outnumber Catholics among young adults.

In fact, among young adult respondents who are Hispanic or whose parents were born outside the U.S., Catholics are the plurality religious affiliation, though the Catholic share has shrunk from 47% to 40% over the last 40 years. Non-denominational Protestants are still a growing portion of this population, and the number of these young adults with no religious affiliation has nearly doubled from 18% to 35%.

And it’s not just that young adults who are Hispanic or have parents born outside the U.S. are more likely to be Catholic - they are also more likely to stay Catholic. Sixty-four percent of those who were raised Catholic still describe themselves as Catholic, while among other young adults only 47% of those who were raised Catholic still identify as such.

Whether that effect will have any staying power remains to be seen. There have been other bastions of ethnic and immigrant Catholicism which have gradually disappeared into the broader American culture over the last hundred years. But for now, Hispanic and immigrant Catholicism seems to have a staying power that other Catholics lack.

Considering the future

Increasingly in the U.S., the default faith is no faith at all. 

Not only is “none” the plurality religious affiliation, but young adults who grow up in non-religious families are more likely to stay non-religious than religious young people are to continue to identify with the faith in which they were raised.

Among those who profess Christianity, the familiar Protestant denominations are rapidly dwindling. With decreases of 70% or more in those identifying as members of the historic Protestant denominations over the next 30-40 years, it’s likely that many congregations will cease to be able to support a church building or minister. Non-denominational Protestantism is the one Christian community which attracts significant numbers of converts, and it will significantly outnumber all Protestant denominations combined within the next 30-40 years.

Meanwhile, Catholicism’s future in the U.S. in the next 30-40 years will increasingly be connected to Hispanics and recent immigrants. Among young adults identifying as Catholic in the GSS from 2018-2022, half were either Hispanic or had at least one parent born outside the U.S.

With these numbers in mind, it is clear that a key challenge for the Catholic Church in the U.S., if it is to avoid the fate of the vanishing Protestant denominations, is how to keep a majority of its young people from defecting to unbelief or non-denominational Christianity.

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