Thomas Frank comes from a liberal political perspective and is highly critical of Republican governance, especially the presidency of George W. Bush (wikipedia), and his film cleverly but subtly portrays evangelical as sincere but misguided authoritarian bigots in contrast to enlightened oppressed socialists who are coming to rescue Kansas from the former.
The reality is that many evangelicals are too trusting of those who purport to be on the side of Traditional Values, and can lack objectivity, but their spiritual and moral values are what has been and is best, while the immorality of the ever-morphing ethos of the western "liberalism" has and is costing American tremendously in lives and money. See stats: http://peacebyjesus.witnesstoday.org/RevealingStatistics.html
Two others aspects that others comment on is the faith of the Founders and the role of religion in politics, in which both sides are often misinformed, or misconstrue reality. The founders were not all Christians, much less all evangelicals ones, but none were atheists, and as a whole reverenced Christ and Christian morality in general, and were not antagonistic towards faith forming moral values and such being affirmed by government, which they themselves did, and Congress often acting much in contrast to the interpretation of the ACLU. The Bible redactor Jefferson even attended a camp meeting-style exhortation in the House by a female evangelist, Dorothy Ripley, along with VP Burr, and a "crowded audience.
The reality is that you cannot separate beliefs from government, with the latter doing so as a reflection of the default religion of the voters, which once was largely evangelical faith. In so reflecting the real faith of the people, today secularism increasingly functions as religion, to America's own hurt.
On the other hand, we should not be so focused on saving the country, which i think has turned a corner it is not going to recover from, and instead the church needs to focus on being an alternative to society. Not exactly the Amish, but more distinctly separate in holiness and attitude, while being more engaging and eager to help than ever. The world is going to need it.