Firstly, I think we need to delineate between people of spiritual faith and religious fundamentalists. They are not one and the same. I agree with you that most people who are religious fall into the first category. However, extreme fundamentalism exists and is no longer fringe in this country. It’s a little naive to not see how they’ve been slowly grasping for power for years. It remains to be seen how to what level of success they will achieve.
To that, I would add that most everyone writes about how evangelical fundamentalists needed Trump to push their agendas. People also write about how he has needed them to cement a base against accountability. Indeed, there seems to be truth in that. Fear of political backlash has kept Republicans from doing their duty and honoring their oaths.
What you don’t hear is how Trump is ultimately expendable to them. You’re correct that Trump could never run a theocracy. But they don’t need him to. They just need him to place enough fundamentalists in positions of power to initiate a take over. After that, it’s anyone’s guess how he will be eliminated. The only thing not in doubt to me, is that he will be if they’re successful. That’s what always happens to stooges.