It seems that the 'the USA is a Christian nation' types have been helping the Defense Dept. write textbooks for Junior Reserve Officers Training Corps (JROTC). So at least argues Talk To Action | Reclaiming Citizenship, History, and Faith, The Department of Defense — Bringing Historical Revisionism to a High School Near You.
It sounds convincing, although I haven't sought to do original research to check it out. [Update: I should add that the part about Jefferson is consistent with what I've read elsewhere — it's the DoD part that I'm taking on faith.]
(And, yes, I know that “antidisestablishmentarianism” originally referred to the reaction against British proposals to disestablish the Church of England, not to the disestablishment of the churches in colonial and post-revolutionary America, but I'm assured it now has a more general meaning also.)