There’s a revealing passage in a report from Kevin Jenkins of the St. George (Utah) Spectrum on an appearance by Cliven Bundy at a gathering of “constitutional conservative” zealots under the aegis of the Independent American Party:
“If our (U.S.) Constitution is an inspired document by our Lord Jesus Christ, then isn’t it scripture?” he asked.
“Yes,” a chorus of voices replied.
“Isn’t it the same as the Book of Mormon and the Bible?” Bundy asked.
“Absolutely,” the audience answered.
Now most “constitutional conservatives” outside a few western states wouldn’t include the Book of Mormon in this syllogism. But the identification of the Constitution (as crucially modified, of course, by a particular spin on the Declaration of Independence) with the Bible as inerrant (give or take a slavery or genocide endorsement) scripture is pretty common to the Con-Con creed. And it helps explain its strength in areas of the country and of the population prone to what religious critics sometimes call Bibliolatry (worship of books as exclusive repositories of divine wisdom).
To any religiously conservative American Exceptionalist, it can make for a potent combination: divine scripture and a divine Founding Document together calling on the Redeemer Nation to rediscover its divine roots and smite the modern infidels or liberalism and relativism and internationalism–by any means necessary. It’s unsurprising this mix of religious and secular themes might have a special attraction to some LDS folk, for whom America has an intrinsically central place in the unfolding of divine revelation (though the LDS authority structure offers a useful break on too much speculation in this direction). But it’s clearly attractive to all sorts of people with a tendency to deify the day before yesterday, and find eternally fixed ways of living and governing in Holy Words.
To put it another way, more often than not American Exceptionalism + Religious Fundamentalism = Constitutional Conservatism.