Christian nationalists do not need the support of a majority of Americans or even a substantial minority : the very origins of the movement were profoundly anti-democratic and remain so. Power is the overriding objective.
So, ah, what if you're an atheist that's sympathetic with the "apocalyptic and Reconstructionist strands of the militant American Christian nationalist, or supremacist, movement"?
Well, you'll be a pretty lonely atheist, because it seems that the lions' share of atheists are leftist socialist humanists. Indeed, most atheists on observation aren't atheists, they are anti-theists; they know there is a God, and they hate His guts beyond imagination. They are little versions of Satan, of whom the book of Revelation (Rev 12:12) says "Therefore rejoice, ye heavens, and ye that dwell in them. Woe to the inhabiters of the earth and of the sea! for the devil is come down unto you, having great wrath, because he knoweth that he hath but a short time."
I saw a sig here on fr that said something like "If there wasn't a God, there wouldn't be atheists." I think that's a pretty profound statement.
Every time I look at the deductions on my paycheck, I can see the imposition of liberal values on America.