Certain folks have taken to describe the current moves to the right a harbinger of a "theocracy." I'm inclined to channel Inigo Montoya and say "I don't think that word means what you think it means."
The nearest thing to a theocracy we currently have going is in Iran, where a council of Shiite mullahs have veto power on laws and who gets to run for office; laws that are un-Islamic in the mullah's eyes get vetoed. That council serves as the analog of the president and Supreme Court rolled into one without any checks and balances; no impeachment and no veto overrides.
There are a few problems inherent in seeing something like that happen in the US; one would assume that it is some sort of Christian theocracy we're talking about, since no other theistic religion would be close to being able to pull that off. We'd either have to have some sort of Spanish Civil War style coup-d'etat where the military and church leaders install a new theocratic government or that the number of Christians grew to a point where the Constitution could be peacefully modified to set up a constitutional theocracy.
Neither seem likely, even though you could always conjure up a movie script where the former could happen. I've seen plenty of scripts where some gung-ho hyper-patriot general comes this close to taking over from "the liberal wusses running this great country of ours into the ground" were it not for the last-minute exploits of our hero; it would be easy to envision a Hollywood writer making General Theodore M. Cratt both hyper-patriotic and hyper-Baptist.
However, Gen. Theo Cratt is rather unlikely to exist in real life. You'd have to combine the devoutness of a Jerry Boykin with the patriotic zealotry of a Curtis LeMay; it's unlikely that such a person would rise to the level of power needed to pull off a coup. Also, there would likely need to be a number of like-minded generals in order to pull that off; just one would get stared down by the rest of the military, even if Gen. Cratt managed to hot-wire some nukes in his command.
Gen. Theo Cratt makes for a good Saturday afternoon TV movie, but a rather unrealistic possibility in real life.
Next, let's look at having a theocracy installed via the ballot box.