The sociologist Robert Wuthnow recently published a book about religion in his home state of Kansas, which he describes as "red state America par excellence." In an interview, while focusing on how deeply embedded faith is in the daily life of many communities, he also explores the long history of interaction between religion and politics in the state:
Sometimes people heard political speeches, like with Lincoln, in their churches. In other cases they heard people talk against the Ku Klux Klan, which is what William Allen White meant in the 1920s when he wrote about churches. In a few cases, they heard from Klansmen who would come marching in to church and basically make a show of themselves (whether by intimidation or people-approved), but the Klansmen tried to connect the churches. So this recent mixing of religion and politics that we have seen so much in relation to the pro-life movement, the anti-gay movement, creationism, intelligent design, and so forth, may be more pronounced, more extreme, and different in that it is driven in and by megachurches, but it’s not entirely new. People have dealt with that question about what it means to be a good citizen and a good person of faith from the very beginning.
What's new is the increasing diversity of doctrines (beyond Christianity and its denominations), the divide between fundamentalism and non-fundamentalism within Christianity, and the absence of faith among many as well. My view is that this increasing – even accelerating – diversity requires us to be less emphatic and more tolerant in our faith-based convictions in the public square – for the sake of public comity. But it is precisely the psychological insecurity of such a neutered public square that fuels fundamentalism. Hence our current polarization.