At the time, Hout and Fischer’s argument was mostly just a theory. But within the past few years, Margolis and several other prominent political scientists have concluded that politics is a driving factor behind the rise of the religiously unaffiliated. For one thing, several studies that followed respondents over time showed that it wasn’t that people were generally becoming more secular, and then gravitating toward liberal politics because it fit with their new religious identity. People’s political identities remained constant as their religious affiliation shifted.

Other research showed that the blend of religious activism and Republican politics likely played a significant role in increasing the number of religiously unaffiliated people. One study, for instance, found that something as simple as reading a news story about a Republican who spoke in a church could actually prompt some Democrats to say they were nonreligious. “It’s like an allergic reaction to the mixture of Republican politics and religion,” said David Campbell, a political scientist at the University of Notre Dame and one of the study’s co-authors.

Granted, the people who were leaving weren’t necessarily at the center of their religious community — they didn’t attend religious services often, perhaps dropping in once or twice a year. But the numbers began to add up, opening a rift between conservatives and liberals. According to Margolis’s research, while young people across the political spectrum tend to drift away from religion, liberals are increasingly unlikely to return.