The difference between what I wrote and the occult, and the fiction associated with cults and religions, is not that I don't think it's true, since they don't think it's true either, and not that I say it's fiction while they say it's true, because there are fantasy and science-fiction writers who jokingly say that their stuff is true, but that I am not trying to make other people think that I think it's true, while they are trying to make other people think that they think it's true.
The thing I wrote is the first time that almost all aspects of the occult have been tied together into one single internally consistent framewaork. Of course, there are elements of the occult that I did not include, such as witchcraft, vampires, and the magic power of crystals. Also, I was unable to include Scientology. Most New Age people strongly support enviromentalism and animal rights, while the Scientologists take an opposite stance and try to maximize the distance between humans and animals. Therefore I went with the former more common view, and didn't include the latter. However, perhaps an imaginative person could include all of these other things also. We can note that one other difference that you tend to see between the occult and cults on one hand and religion on the other. The occult and fiction associated with cults tends to be more logical and rational, and less far-fetched than the fiction associated with religion. As strange as my thing was, I did not say that the Old Ones created the entire Universe. Compare my thing with saying that not just the Solar System or the Galaxy, but actually the entire infinite expanse of the entire Universe was somehow intentionally delibrately made by some sort of conscious omnipotent entity. There's no basis of comparison. Therefore, the fiction associated with religion tends to be far more far-fetched and ludicrous than the occult or the fiction associated with cults.
No one could imagine a person actually thinking that not just the Solar System or the Galaxy, but the entire Universe was somehow intentionally made by some sort of conscious omnipotent entity. If you were to try to make someone think that you actually think this, you would have a 100% chance of failure since no one could imagine a person actually thinking this. Therefore religious people aren't trying to make people think they actually think this, since no one could imagine someone actually thinking that. However, with the occult and cults, they are trying to make other people think that they themselves think it's true, although no one actually thinks it's true. In some ways, religious people are more like J.R.R. Tolkien in that they say it's true but aren't trying to make other people think that they think it's true, then proponents of the occult or cultists who are trying to make other people think that they think it's true.
Lastly, I just want to point out that my hypothetical cult fiction could be used as a basis for a suicidal cult by saying that the group has achieved perfection like Heaven's Gate. It could also be the basis of a homicidal cult by saying that the mechanism by which the Old Ones will destroy the world includes the devoted loyal Chosen going out and destroying it on their behalf.