Why combine religion and sexual orientation?

Within the White sub-group, the most impactful further split is by religion. It starts off simply: White Evangelicals these days greatly favor Republicans over Democrats. But, then, equally true: When you look at White Jews, White Buddhists, White Atheists, and White Agnostics, you’ll see folks as likely to favor Democrats as White Evangelicals are to favor Republicans. There are then other religious identities in the middle, some of which lean to the right — including non-Evangelical Christians of different varieties (Protestant, Catholic, etc.) — and some of which are center/left on average, including mushy categories like “nothing in particular” or “other” (which I suspect contain a mix of people who think of themselves as Christian and people who don’t).

But then sexual orientation is also a really big deal here and operates essentially identically to religion such that, for example, I don’t think you can find any interesting political differences — not in party identification, not in ideology, not in specific issue opinions — between White Atheists/Agnostic and White Gays/Lesbians, especially as you move up the education ladder. Both groups are overwhelmingly liberal Democrats; both groups tend to be especially liberal on issues that relate centrally to religiously tinged issues involving sexual activity and reproduction — gay marriage, abortion, pornography, sex ed, and so on.

It makes sense to combine the two groups, especially because there typically aren’t a ton of non-heterosexual folks in these samples — gays and lesbians make up less than 5% of the American public. So, you run out of data quickly if you, e.g., make a sub-group that’s just gay and lesbian Whites. You’ll miss some interesting stuff downstream.

What exactly do I mean by Heathens and Evangelicals?

The term “Heathens” on my definition is anyone who indicates that they fall into any of these categories: atheist, agnostic, Jew, Muslim, Hindu, Buddhist, not heterosexual (gay, lesbian, bisexual, other), not male or female (i.e., non-binary), and/or transsexual. And I’m using “Evangelicals” to mean that they either indicated they were “born again or evangelical” and/or Mormon (both of which strongly signal Republican identification among Whites).

You can get people who are both Evangelicals and Heathens — a gay Evangelical, for example (rare, but they certainly exist).

For my final mutually-exclusive groups: “Evangelicals” are Evangelicals (as I just described them) who are not also Heathens. “Heathens” are Heathens who are not also Evangelicals, and everyone else is in the middle (i.e., mostly people who are both non-Evangelical and non-Heathen, but also the relatively small number of people who are both).

Why the additional split in the middle group that is neither purely Heathen nor purely Evangelical?

I went ahead and made a less-impactful split of those in the middle into people who explicitly said they were Christians (Catholics, mainstream Protestants, etc.) vs. those who said “nothing in particular” or “other”. My motivation here was similar to when I split non-Blacks into Whites and Hispanics/Asians in my initial cut — it’s a pretty important distinction that will get introduced soon anyway, so better to go ahead with the split now to increase the understandability of later sub-sub-groups.