At the end of this FiveThirtyEight post about the big issues in the election, Leah Libresco has a bit about religion and social issues and how they may play out that references the big Pew Religious Landscape study with respect to party affiliation by religion. And, this being a FiveThirtyEight post, she has a chart. See?

Screenshot 2015-11-19 15.55.03

As the chart shows, certain religious groups skew more substantially to one party or the other. In particular, black Protestants, non-Christians and the unaffiliated skew strongly Democratic, while white Evangelicals and Mormons skew strongly Republican. Catholics and mainline Protestants are pretty evenly split.

This, of course, is not news. We’re a religiously polarized country; we know this. But, I wondered, has this polarization strategy reached a point of diminishing returns? Have we reached the point where either or both parties need to start reaching across the divide to prevail in close contests? Or do we potentially have even further to go down this polarized road?

To answer that question, I took a look at the Pew data and sliced it a bit differently. Rather than take a look at each religious group and how they skew by party, I decided to look at each party and see how they skew by religious group. Assuming that the Pew data is of registered voters (which I couldn’t determine readily if it was or was not), multiplying that data by Libresco’s numbers for percentages of the U.S. population and percentages of each group that is registered should give demographic weights for each group within each party.

And, I should stress, I didn’t look only at the breakdown of the politically affiliated. I also looked at the religious breakdown of that group which leans toward neither party. This group, after all, is the low-hanging fruit for any electoral strategy aimed at mobilizing voters by religious-based identity politics.

Here’s what I got:

Religious breakdown by party

As expected, the religious composition of the party coalitions differs starkly each from the another. Approximately 40% of the GOP electorate is white Evangelical, while only about 12.7% is religiously unaffiliated and a negligible percentage is black Protestant. By contrast, among the Democrats 26% is unaffiliated and 13% is black Protestant, while white Evangelicals make up 17.5%. Catholics and mainline Protestants make up similar percentages of each coalition, and other groups – “other” Christians (mostly Mormons but also Jehovah’s Witnesses and Orthodox) and non-Christians (Jews, Muslims, Hindus and Buddhists) – make up relatively small proportions of either party coalition.

But what’s most interesting to me is the breakdown among those who lean to neither party. And what’s interesting is that among the politically unattached, the two largest groups are the religiously unaffiliated and white Evangelicals. Indeed, the religiously unaffiliated are a larger percentage of the politically unattached than they are of the Democratic coalition – and the relatively weight of white Evangelicals among the politically unattached is larger than the relative weight of any other group, including Catholics and mainline Protestants, within the GOP coalition. Together, the two groups represent more than 50% of the politically unaffiliated – several percentage points higher than their representation among the politically affiliated (Democrats plus Republicans).

What that suggests to me is that there are still gains to be made for both parties by pursuing a strategy of religious polarization. Rather than moderate its image on social issues, the GOP could further cement its image as the party of white Evangelical Protestants, and try to win converts from the substantial number of politically unattached Evangelical voters. Similarly, rather than make overtures to religious voters, the Democrats could double down on their identification with the irreligious, and try to win votes from the religiously unaffiliated voters who do not currently lean toward either party.

Needless to say, these identity-politics-based strategies would be mutually reinforcing. The more the GOP pursues the path of polarization, the easier it is for the Democrats to make gains by doing the same, and vice versa.

And since Catholics and mainline Protestants are the fastest-shrinking groups, that calculus is unfortunately unlikely to change any time soon.