Fun With Stats: Dwindling Christianity

Religiosity is declining in America. In 1948, the first year Gallup began tracking America’s religiosity, 91% of Americans identified as either Protestant or Catholic. In 2018, the total percentage of Christian Americans, which now tracks denominations beyond Protestant and Catholic,was 67%.

Much of this rapid decline occurred after 2000. In 2000, 80% of Americans identified as Christian. Since then, Christian affiliation has fallen by a whopping 16%. In that same time, Americans who identify as having no religious affiliation have increased from 8% to 20%.

Below is a graph showing this decline. The steepest decline has been among Protestants. Catholic numbers have fallen too, but not as impressively as Protestants. The remaining non-Catholic Christianities have actually increased in numbers since 2000.


I built statistical models using Gallup data from 2000-2018. I omitted inclusion of pre-2000 data because it seems intuitively less predictive of future patterns than post-2000 data. Though Christianity’s numbers were falling before the turn of the century, the rate of decline increased after 2000.

I used these models to predict future growth or decline of Christianity.

The fields below show a range, which represents a 95% confidence interval, of anticipated Christian affiliation in the coming decades.


My models, which all used Caret-machine learning linear models in the statistics package R, anticipate a roughly 1% decrease in association in all Christianities per year. If these models hold, America will have fewer than 50% Christians between 2040 and 2050. If recent trends hold, American Protestantism may be entirely gone by then. These models also show those Americans with no denominational affiliation will represent about 40% of Americans by 2050, doubling its current number.

Interestingly, these models also predict alternative Christianities will increase during this time, and Catholicism will only trend slightly down.

Of course, there is a chance trajectory slows during this time, rendering these estimates entirely incorrect. But I was unable to find a realistic model which anticipated this, given the steep drop since 2000.

Below are predictions in graphical format from now until 2050.


Author: Tim...Stepping Out

Tim Stepping Out

12 thoughts on “Fun With Stats: Dwindling Christianity”

  1. I think one of the reasons why Catholicism is dwindling is because of its sexual abuse scandals like priests molesting altar boys and the upper echelons (the archbishop of the diocese or even the Pope) will try its best to elude prison time by reshuffling. I can’t really speak about Protestantism because I’m an ex-Catholic. I live in a Catholic majority country (~80%) but some of the people I’ve spoken with are either closeted atheists like me or not really as devout as they were once was. What could be more BS than devout Catholics blaming the devil and homosexuals for them molesting young altar boys? I believe they deserve incarceration just like a person who committed theft or treason.

    This reminds me of Betty’s lampooning of the Pope as the head of the world’s largest pedophilia crime syndicate. 😄

    Liked by 3 people

    1. I was surprised that Catholicism is not falling very fast in America. Catholics have always been a minority in America, but they remain in the mid 20%s, despite the outrageous behavior of their church.

      What I found interesting as I started to look at the data is how steeply Protestantism has fallen. Prior to leaving religion, I was a Lutheran. The churches I attended were not particularly concerned about implanting a broad ideology in their congregants (at least from what I remember). This doesn’t seem to be the case with the loudest Evangelical or fundamentalist denominations in America…at least from what I can tell. Given the fact that those groups are basically monolithic in their social and political positions, I have to assume there’s a steady stream of thought control going on in those denominations.


      1. Let’s not forget the fact that some priests and pastors are closeted atheists.

        I wouldn’t be surprised if some of these closeted atheists of the clergy are also into thinking that Jesus was a myth all along. I’m sure some of them like the Jesuits and Dominicans have read the works of Joseph Wheless (Is it God’s Word and Forgery in Christianity), FC Baur, or even Walter Richard Cassels.

        Liked by 1 person

  2. It’s heartening, although I’m sad to report evangelicals are on the rise here in Brazil. Overall, religion is in decline here, but the evangelicals are eating into the traditional Catholic population who seem to like the more charasmatic zeal of the new preachers.


      1. Odd country, this one. Enormously prone to superstitious belief. In the US, I see evangelicals cementing themselves in the rural towns, where they can still control the narrative of the young. Overall, though, it won’t be healthy for the US as there’ll be a divide cut down faith lines.


  3. Have you written about Galatians 2:11-21 where Paul rebuking Peter in Antioch is actually about the conflict between Petrine and Pauline Christianity? Could this mean a conflict between different Gnostic and/or Jewish Christians?



    1. It was also a cipher, or perhaps recast as the fight between Simon Magus and Peter. There are various places throughout the Ebionite Pseudo clementines that show the Petrine side of this debate. I’ll be publishing a 40 minute YouTube video in the next couple days about Simon Magus where I discuss this a bit. I’d recommend Aeon Byte interview with Robert M Price on Simon Magus as a great entry point on this topic.


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