J.D. used to tell us that Americans fought for their homeland, not for a creed. Now he thinks that American exceptionalism traditionally revolved around conservative Christianity, which is under threat from secular elites. Furthermore, he believes that our Christian character is threatened by immigrants. Does any of that make sense?
No. Christianity doesn’t make us exceptional; to the extent that America is, and has ever been, a Christian nation, that character ties us to vast numbers of people outside our boundaries, including nations for whom Trump has nothing but disdain. In addition, a large proportion of the illegal immigrants entering our country through Mexico are Christians. The logical way to refresh our supposed character would be to let them in.
Christianity has waxed and waned throughout American history. It was waning at the time of the Revolution and the writing of the Constitution. Nothing in the Declaration or the Constitution suggests that Christianity is at the heart of the American creed. Vance is really closer, at this stage of his life, to a 19th century French royalist than to Washington and Jefferson.