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.