America is moving toward theocracy, so should atheists or agnostics care?
There's certainly an element of authoritarianism at present, but it's not apparent to me that the US is moving towards a theocracy. Mid-terms are one year away, and the next presidential election is 3 years away. An opportunity to elect a new round of rascals!
Personally, I think the opposite is happening. What you see now, blasted all over the media, is imho, a sort of last ditch revivalism. Look at all these doomsday predictions, all these multimillionaire televangelists flaunting their material goods. I just don't think it's sustainable. I want to think people are smarter than that and will, at some point wake up and realize they've been hornswaggled (yes, I did use it), and begin to reject the nonsense wholesale. Maybe that sounds like wishful thinking, but I can't envision going the other way.
I think you should read the definition of theocracy...and there's no danger of America becoming one. That sounds more like anti-Trump sentiment and fear mongering. The U.S. is a free country with a Constitution that may as well be written in stone.