It goes against Scripture for one thing, but it's also (usually) contrary to the 1st Amendment. The term means too many things to accurately critique it--it depends on who's saying it--but that's exactly how it is being exploited: taking the theonomists' extreme version of it, making that the given meaning, then saying they're "unconstitional" for wanting to remove the 1st Amendment and establish Christianity.

I think the whole thing -- the revived Christian Nationalism -- is a trap.