His spiritualist writings come early in his career- before the dodgy ordinations. He says he's channelling his father-in-law- a minor Victorian architect- and two of his father's otherworldly mates- one of them a businessman and the other a swindler and murderer known as The Officer. Father-in-law gives us information about the lower realms of what I suppose we must call purgatory, where he is carrying on his studies in Renaissance architecture in a heavenly recreation of Queens College Oxford as it was before it was rebuilt (because good buildings also go to heaven when they die.) The businessman- too good for hell, too materialist for heaven- mostly pootles about on the astral- where dinosaurs chase him through the carboniferous forest which once existed on what is now the Thames embankment. And the Officer- as bad a man as you could hope to avoid- goes down to the depths of hell and then clambers back (because this is the 20th century and we're all liberals here and hell is no longer eternal.) His adventures- taking in the City of Hatred- which is ancient Rome gone all rotten and slimy- and the City of Lust which is ancient Corinth- are never a step away from allegory and suggest nothing so much as a mash-up of the Pilgrim's Progress and a fever dream. He defeats and tortures an inquisitor, leagues himself with the Emperor of Rome and leads a rag-tag army of pirates and mercenaries against Danton's sans-cullottes. No-one dies in the battle because everyone is already dead- but being carved up with a cutlass still hurts. Only don't for a moment suppose that a spirit body which feels pain can also feel pleasure- because it can't- as you'll find out if you go to the City of Lust expecting to have fun.
How much of any of this do I believe?
These days accounts of the afterlife (as found in The Michael teachings or Michael Newton's Life Between Lives) have dropped the circles of Hell and replaced them with reincarnation- for all the world as if God has changed his mind. I like reincarnation better but perhaps it's only a more sophisticated formulation of the idea that enlightenment has to be sweated at. You expiate your sins in hell, you pay off your karma through successive incarnations: the words are different but suffering is suffering wherever you undergo it- and the supposed outcome is the same. One can only use the symbolic language one's audience will understand- and in the early 20th century reincarnation was just a weird, Blavatskian shimmer on the horizon. Revelation has to be thinkable, otherwise it's nothing but gobbledy-gook.
In other words, don't expect books like this to tell you anything you don't already know.