by Ryan P. Burge, Eastern Illinois University

I make a lot of data visualizations. Most of the time I have a pretty good idea of what the results of the calculations are going to look like before I write the code. In fact, some of the results are so obvious that I don’t even post them anywhere, they just live on my hard drive until it fails. Then sometimes I make some graphs that I stare at for a long time and am still finding new things that I didn’t see on first inspection. That’s what happened over the weekend. To give some context, I was thinking about how little I really understood the religious composition of the two major parties back in the 1980s and 1990s. It’s well known that the Religious Right has been transformative for American politics, but how has that changed the makeup of the Republican Party? And, now that religious nones are a quarter of the population, their presence must be felt by the Democrats and the GOP.

So I just did some simple analysis.

I grabbed the General Social Survey and then made a snapshot of the religious composition of both the Republicans and the Democrats, every ten years starting in 1978. I did make one modification to the traditional RELTRAD categories by combining Jews, those of minority religions (Buddhism, Hindus, Mormons, etc), and those that go unclassified in RELTRAD into a single category that I called “other faith.” It makes interpreting the graphs much easier. Let’s get right to it: this is the religious composition of the Democratic party over the last forty years.

The first thing that jumped out to me is that the largest contingent of Democrats in 1978 was Catholics, followed by *evangelicals* at 22.4%. Let that sink in: nearly a quarter of all Democrats in 1978 were evangelical Protestants. Mainline Protestants followed closely behind at 19.4%. Black Protestants were 12.4% of Democrats (and basically haven’t really changed over time). The nones were about 9% of all Democrats.

Then things shifted, a lot. 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. The share of Democrats who are Catholic has shrunk basically the same amount, ten percentage points. And, the Democrats have lost share among evangelicals who are now 14.1% of Democrats, which is higher than I would have guessed now and still the third largest group among Democrats.

That’s a lot of losses. In total that’s about 27% of losses between mainliners, evangelicals, and Catholics. Where did the gains come from? Well, mostly from the nones. In fact the share of Democrats who identify as nones has jumped almost twenty percentage points since 1978. At the same time, those of “other faith” have increased significantly as well, by nearly seven percentage points. And 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.

How about the Republicans? In 1978, two out of three Republicans identified as evangelical or mainline Protestant. That is still stunning to me. As we have written before, we need to jettison the idea that mainline Protestants are the “liberal” type of Protestant Christianity, when in their heyday, mainliners were twice as likely to be Republicans as Democrats. On the right side of the graph we see that Catholics made up 18.6% of Republicans, while the nones were about 5%.

Some of the changes within the Republican coalition are staggering. For instance, the 40% of all Republicans that were mainline Protestants has now shrunk to 15%. That’s a 25 point loss by one group. And, again, that’s basically because mainline Protestants are now a third the size they were in 1972. That’s really the group that has seen a drop off among Republicans. How about gain? Well, evangelicals are up, but not as much as people would likely think: just 7.6%. Today, it’s accurate to say that one third of all Republicans are evangelicals – which means that this is the largest faith group contingent in either political party. There have also been some significant gains among Catholics, as well, at just over six percentage points. That’s not terribly different than the gain among evangelicals, but this is a story that seems to go uncovered by the media. It’s also notable that the nones are now 13.6% of the Republican coalition. In fact, the nones are about the same portion of Republican as mainline Protestants. 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.

It’s somewhat comforting to note that neither of the two major parties in the United States are dominated by one specific religious group. I know that tons of articles are written the link between evangelicals and Republicans, but the data indicates that over two thirds of Republicans today are not evangelicals. The same is essentially true for Democrats as well. The largest group for them (the nones) make up just three in ten Democrats today. There is room in either tent for a member of any religious group.

Ryan P. Burge teaches at Eastern Illinois University in Charleston, Illinois. He can be contacted via Twitter or his personal website. The syntax for the post can be found in here.