Gushee errs in one major way - there was nothing leftist about slavery at the founding, disenfranchised women, etc., although the categorization into left, middle, right is so subjective that most anyone can make their case using their own definitions.
That aside, Ayn Rand...you need to read my article of 2011, .
There is a target audience for anti-libertarian, religiously based reaction such as you give here but the target doesn't include the vast majority of Southern Baptists who are far close to the middle than the foaming-at-the-mouth dystopians; nonetheless, we could both find individuals, probably some scientists as well as clergy, who are purebred libertarians.