If you’ve seen charts dealing with religion in the U.S. over the past few weeks, there’s a good chance they came from Professor Ryan P. Burge of Eastern Illinois University, who’s been using 2018 data from the General Social Survey to show the latest faith-related trends.

His latest posting concerns the change in the religious makeup of the two major political parties.

Burge looked at snapshots of who made up the parties every 10 years beginning in 1978. Check out the Democrats:

You can see the evangelicals (blue, on the left) shrinking from 22% of the party in 1978 to 14% today. Mainline Protestants are cut in half. Catholics lose some weight, too. In fact, the biggest change over the past 50 years is that Americans with no organized religion have tripled as a constituency, from 9% in 1978 to 28% today.

“Nones” are the largest single group in the Democratic Party.

Burge summarizes:

The percentage of Democrats who are mainline Protestants has shrunk in half from ~20% to just 10% now. That’s not due to a mainline exodus toward the Republicans, that’s due to mainliners disappearing altogether… … … that’s really the entirety of the shift for Democrats: losses among evangelical and mainline Protestants and Catholics with huge gains among the nones and the others.

What about Republicans? Before you see the numbers, you might expect a decline in Nones over time and a drastically growing percentage of evangelicals.

In fact, both of those predictions would be wrong.

The evangelical slice of the pie grows… but not all that much, from 25% (in 1978) to 33% today. Evangelicals make up only a third of the GOP today! You would never know that watching FOX News, but there you go.

The biggest drop, once again, came from Mainline Protestants who are becoming something of an endangered species.

As for the Nones, they became a larger constituency over time, going from 5% of GOP voters to 14%. That is shocking to me.

Recall earlier that the Democrats have gained about 20 points from the nones, but the Republicans gained nearly nine points themselves. So, it’s not accurate to say that the nones are completely captured by the Democratic Party; instead if one just looks at partisanship nones it appears like two thirds of them are Democrats, and the others are Republicans.

What does this mean for the candidates? It’s foolish for Republicans to cater only to evangelical Christians when the majority of GOP voters don’t belong in that group. They haven’t learned that lesson, at least given the way the Trump administration acts.

On the other side, it’s wise for Democrats to remember they have a diverse base, 40% of whom are not Christian. Many of the Christians, too, don’t want to see their faith co-opted by politics. All the more reason to stay away from the God chatter altogether, or at least to bring it up only in benign ways. Democrats are not about to elect a Christian preacher to high office.

