I can tell you from experience that A Beka (and Bob Jones University Press) are stridently against modernism in all its forms. (I’m assuming they’re against post-modernism, too, but you have to understand that the opinions and perspectives this sort of Christian fundamentalism has about society and culture were formed between the late 1920s and early 1970s and, because of this, the culture wars that they are fighting often come across as confusingly antiquated. Thus, the ongoing obsession with the imminent threat of Communism. See also: Why I sat through multiple sermons on the evils of rock n’ roll in the late 1990s.)
If you associate modernism primarily with abstract art, Scandinavian furniture, and houses made out of glass, then all of this is probably just as confusing as set theory, itself. But art isn’t really what the fundamentalists are thinking about when they think about modernism.
Instead, they see modernism as the opposing worldview to their own.