Gallup classifies Americans as "very religious," "moderately religious" or "nonreligious" based on their responses to questions about the importance of religion and church attendance.Moving from CA to TX, as I did in 2003 for a post-retirement one-year visiting professorship, was an eye-opener for me. CA is below-average in religious involvement whereas TX is above-average.
Most of the top 10 highly religious states over the past nine years have been in the South, except for Utah, where the highly religious Mormon population helps put it in the top 10 consistently.
The least religious states have typically been concentrated in the upper Northeast, Mid-Atlantic and Northwest regions.
Gallup began tracking religious indicators daily in 2008. The percentage of all Americans who are very religious has declined slightly over that period of time, from 41% in 2008 to 38% in 2016, while those who are nonreligious has edged up from 30% to 32%.
When I assigned MBA students in TX to do professional development plans I was amazed by the number who included increased church involvement in their personal development profiles. In CA perhaps one student in a grad seminar of 25 would mention religion in their life plan, in TX upwards of a third would do so.
Gallup's map of religious involvement by state almost could be mistaken for a map of which states voted for which presidential candidate. Most low involvement states voted Dem while most average and higher states voted GOP.
Coincidence? Not likely. Particularly revealing is CO which reports below-average religious involvement. It is surrounded by above-average states.
CO has gone from reliably GOP red to pinkish-purple trending Dem, largely based on migrants from CA and other blue states. It isn't too big a stretch to say the Democratic Party has become the secular party.