Razib's informative post relating Asian-American religious affiliation to electoral behavior spurred me to take a look at the relationship between regular church attendance and partisan affiliation among self-identified Christians in the US over the last several decades. My impression was that the difference in attendance rates by party have become starker over time, Jimmy Carter being more overt about his religion than Barack Obama is and Gerald Ford being considerably less so than the second George Bush was while in office.
It's important to keep in mind that we're looking at those with either a Protestant or Catholic religious affiliation. Non-Christians and those without any religious identification at all are not considered. In a subsequent post I'll take a look at religious affiliation by party over time, but for now let's just consider expressed piety (evaluated by whether or not a respondent attends services on at least a weekly basis) among those who identify as Christians. To avoid racial confounding, the analysis is limited only to whites. Note also the range display from 15%-45% of the self-identified Christian population. Even among white Christian Republicans, it has persistently been the case that only a minority attends services on a regular basis:
Independents and moderates are, on the whole, less knowledgeable and less actionable than committed ideologues and partisans are, and that shows up here as well. The tendency among Christians for Republicans to be more religiously active than Democrats and moderates existed at least as far back as the early seventies, continued over the course of that decade, and had become pretty firmly established by the time Reagan left office. The partisan gap has only widened since then.
That said, the differences aren't stark. Today we'd report them by saying that while 4-in-10 Christian Republicans attend services at least once a week, only 3-in-10 Christian Democrats do. Quite similar, really. I suspect the bigger story is in the drop off in Christian identification among Democrats (but not among Republicans) over the same time span.
GSS variables used: RELIG(1-2), RACE(1), PARTYID(0-1)(3)(5-6), ATTEND(0-6)(7-8)