This is something that has been fermenting in my mind for quite a while. I ran into an article that puts my thoughts into words quite well:
I know most here aren't Christians, but it seems that the right-wing 'evangelicals' who exclaim about signs of the end, themselves qualify as perhaps the greatest sign: the New Testament prophesies that "the love of many will grow cold" and foretells that many will have the form of religion but not its substance.No principled reason can be given for the distinction the Christian Right draws between harnessing the state to pursue social objectives and harnessing it to pursue economic objectives. It is a uniquely American distinction as far as Christian politicking goes. What the distinction reveals is that so-called values voters are just a particular flavor of right-wing political culture, one that opts for Christian language and rhetoric when communicating its message. But in that case, it is their freestanding political commitments that inform their Christianity, not the other way around.
The answer to this riddle is therefore not so mysterious. Although nominally interested in harnessing the state to pursue Christian social objectives, the American Christian Right is not detached from the culture it has developed within. Their politics is not one that is Christian in origin; rather, it originates from the same place all other right-wing politics originates, but mobilizes Christian rhetoric and meanings post-hoc to justify its goals.