As it turns out, that narrative has it partly backward. It’s not just that our religious beliefs affect our politics — it’s that our politics affect our religious choices. We don’t just take cues about politics from our pastors and priests; we take cues about religion from our politicians.
The familiar explanation is that this religiosity gap arose because religious Americans shifted into the Republican Party while less religious and secular Americans became Democrats. Supposedly, this sorting began in response to the changing political landscape of the 1970s and 1980s, when social issues were intensely debated, religious elites like Jerry Falwell rose to prominence, and Republican politicians increasingly focused on morality and faith.
Faith often becomes a peripheral concern in adolescence and young adulthood — precisely the years when we tend to form stable partisan attachments. Religion typically becomes relevant again later, after we have children and start to think about their religious upbringings.