One of the more common themes in political reporting is to track how different religious groups vote on certain issues. Ever since Trump got elected there has been a lot of reporting on Evangelical support for Trump (an issue I’ve posted about previously), and other topics are framed through the religious lens as well.

This discussion came up again from a different angle this week when Ross Douthat published a column praising WASPs, and people (including Ross himself) ended up discussing who WASPs were today. This led to a few exchanges that showed people debating whether it was fair to call today’s Evangelical Christians “Protestant”.

It’s an interesting question, and one that can be hard to parse if you’re not part of either group. Having been raised in Evangelical churches and schools, I would say that most Evangelicals consider themselves a subset of Protestant-ism as opposed to a separate group, but would agree that there are noticeable differences between the groups. The polling companies generally address this issue by calling groups “Evangelical” vs “Mainline Protestant”. PBS did a quick summary of what the differences in belief are here.

From a polling perspective Christianity is the most subdivided religion in the US, probably because Christianity is the most popular religion in the US. Here’s how Pew Research breaks down Christian respondents:

The orange arrows mean you can expand the section to see what was counted under it. Go here for the full clickable table to see who is in each bucket.

This shows that while most of the country (70.6%) claims the Christian faith, the exact flavor can vary. Evangelicals are the largest group, but Catholics are the largest denomination. Some of the denominations listed are not even particularly accepted by many Christians as part of the Christian faith, such as Jehovah’s Witness. Racial history is also used to subdivide religious groups. Confusingly for anyone not well acquainted with the topic, many churches with the same names actually can fall in three different categories. For example, Southern Baptists (5.3% of the US) are Evangelical, American Baptist Churches (1.5% of the US)are Mainline Protestant, and the National Baptist Convention (1.4% of the US) is a historically Black Protestant denomination. Overall, someone referencing a “Baptist” is most likely talking about an Evangelical type church (9.2% of the US) or a Historically Black Protestant Church (4% of the US). Mainline Protest Baptists are only 1.5% of the US.

For other religions, Pew breaks down “World Religions” (those having large numbers of adherents elsewhere in the world, but small numbers in the US ) and “Other Faiths”, which are basically Unitarians, New Age Religions and Native American traditions. For World Religions they include Judaism, Islam, Buddhist, Hindu and “other”.

When using race and ethnicity in breakdowns, the Public Religion Research Institute actually takes it a step further than Pew, and subdivides Catholics in to “Hispanic” vs “non-Hispanic”:

Finally, there are the “nones”. This group is currently the second biggest group in the US, big enough that Pew has started subdividing it as well:

As you can see, “none” sometimes mean a specific belief (atheist, agnostic), none by default (nothing in particular, religion not important), or seemingly non-committal (nothing in particular, religion important). These groups make up nearly equal portions of the 22.8% of people in this category.

Of course with all of these categories, it’s important to remember that this is all self-defined. No one checks that someone calling themselves a Baptist of any sort actually goes to church or even believes in God. Given that about 50% of people in the US say they rarely or never attend church, this definitely can skew things.  This has led some surveyors to split out “regular church attendees” vs those who don’t often go. Conversely, on the atheist side, Scientific American reported that 1/3 of people who call themselves atheists stated that they believe in some form of life after death, and 6% said they believed in resurrections.  Because of this, some groups have started to come up with new ways of categorizing religious people based on participation and belief levels.

So what’s right here? Should we categorize based on self-identification, participation, or belief? Well, I think it depends. Each of these things can be important depending on what your question actually is, and it’s important to know how surveyors or study authors addressed these issues before drawing any conclusions. It’s also probably important to remember that the distinctions drawn in US surveys are simply reflective of the US population. Muslims aren’t lumped together because Islam is a monolith, but rather because it would be hard to get a meaningful sample size of Sunni vs Shia in the US. If the population of the US shifts, we may see different groups highlighted.

If you know of any other interesting ways of breaking down religions, please let me know! Categorizing belief systems is an interesting challenge, and I like seeing how people address it.