Religious elements tend to focus around christian symbolism, presumably because of Akira's family. Bible quotes, crosses, angels, general moralism around sin, even the notion of 3 gods being 1. One could argue that the eternal struggle between light and dark with humanity being the rope in between them is from Manichaeism, but that has been since incorporated into christianity so I guess it's nitpicking. That would be the same for most of the random elements that are thrown around.
Occult elements are hard to pinpoint because what is presented doesn't necessarily refer to any specific occult element rather than having an occult feel to it. "The old one" for instance (and even NAO), could simply be Selebus' creation, rather than a Lovecraftian reference. Same goes for the sakura trees and the world itself - and to a larger extent, things like wires, semen and voices in your head seem to be very much a Selebus "creation" rather than a specific reference to something. Of those there are countless, and for an example of what I mean: You could find numerous references of secrets hidden in the wind or in the voice of cicadas in occult literature, but to say Selebus is making a direct reference to one of them would be forcing the point imo. It doesn't seem to be the case.
There is also random stuff that he throws in that I don't think merit a real analysis. You could argue that Flora, the Emissary of Pegasus, the Council of Plants, the Untitled tv show, and so on, have counterparts in movie and literature culture as a whole. But to each their own in terms of what to delve into.
You haven't asked, but it is important to note that although there aren't many specific occult references, there are many poetry ones. Those tend to be blatant enough that you'd recognize them though, so if anything sounds like classic poetry to you there is a likely chance Selebus is referencing something.
There are a few references to architectural landmarks, paintings, movies and videogames too - but those are in the extreme minority. Strangely enough, I don't remember many references to literature novels though (I can only recall "where the sidewalk ends", but even that is not exactly classic literature, as he tends to use classic poetry). I guess Akira's deal really was poetry...
