"The conflation of sacred and secular metaphors mobilized intellectuals just as much as it did backwoods farmers who were tilling the stony glebe." -- Reiner SmolinskiThe issue of apocalyptic imagination is interesting because these biblical texts and texts – even if they’re not fully worked out in any theological way into an eschatology, even if they have no theological effect or academic force – definitely provides an imaginative language and inspiration. The apocalyptic imagery is powerful, and moves people.
"The quest for salvation provided imaginative participation in the last things." -- James H. Moorhead
Look at the Timothy Dwight poem, "America," which had very secular function, a public, inaugural reading, I think, but deploys images -- the military metaphor, here, is exactly right -- straight out of St. John's end of the world: “Then, then a heavenly kingdom shall descend,/And savage nations at thy scepter bend” and “Till the last trump the slumbering dead inspire,/Shake the wide heavens, and set the world on fire.”
You see it too in the Nat Turner text, his Confession, though it’s not very theological, it’s not very worked out and there’s not an elaborate hermeneutical explanation of time lines or eschatological specificities, but the millennialism is a force, unstoppable, inspirational and elemental: “I had a vision – and I saw white spirits and black spirits engaged in battle, and the sun was darkened – the thunder rolled in the Heavens, and blood flowed down in steams.”
Frederick Douglass does this too, even though, basically, religion, for him, for the most part, has been another tool of slave masters. The most devotional have also been the most cruel, for him, but then he in a moment of need he breaks out in a quasi-apocalyptic prayer song: "Does a righteous God govern the universe? And for what does he hold the thunders in his right hand, if not to smite the oppressor?"
I think it’s worth noting, at least, sort of, parenthetically, that one of the functions of millennialism hasn’t been theological, and isn't explicitly interpretive, but rhetorical and inspirational and a force of the imagination.
Timothy Dwight's wanted to write epic poems on and for America; Nat Turner said the "the Holy Ghost has revealed itself to me" and was inspired to kill whites; Douglass, the father of African-America oratory, tells his story in the form of a secular salvation narrative.