What is the technical term for the belief that God did not create the mechanics of the universe but only its substance?
The term you’re looking for is “heresy”.
It sounds vaguely like Deism. Though I’ve never heard it described quite that way.
A physicist might argue that substance (matter and energy) and mechanics (the movement of matter and energy) cannot be separated. I suspect that you are thinking of deism, which might be described as the belief that God created the universe with its substance, mechanics, and initial conditions, and then let it run its course according to its design. It’s like a skilled watchmaker who builds a watch that keeps time well, so he does not have to keep adjusting or correcting its time.
I am writing a story in which there is a group of zealots. They believe that the ‘laws of nature’ are really the mind and spirit of a malevolent, quasi-divine being. They believe the material universe was created by God, within and according to the laws of nature, in order to destroy those laws and thus the malevolent being. The god of the zealots is active in the world; as though he were playing the laws of nature like the strings of a violin.
This would not be deism, would it? How would you label the zealot’s beliefs? I ask because, for my notes, I would like to have a precise term to reference it by.
You are right, that’s not Deism. It sounds a bit like Gnosticism or Manichaeism. I’m no expert, but from the little I’ve read about it, such ideas were common in ancient religions around the world. Of course, Christianity also speaks of Good vs. Evil, Light vs. Dark, God vs. Satan, and so on. The difference may be that Christianity (and Judaism) believe that God alone created the universe and everything in it, God said it is good, and God alone is Lord and Ruler of all Creation.
I couldn’t say whether there are ancient origins of the split creation you outlined, with malevolent beings creating the laws of nature and God creating the material or substance. Sounds like an interesting variation though.
It seems like a type of Platonism, where Laws exist as some type of platonic form separate from God and his creation. But that’s probably not the technical term you are looking for.