Astral Travel in Heaven and Hell

Like the descriptions of the mythological faery realms and the realms of pagan gods, much of the descriptions of the Christian heavens and hells were undoubtedly received through astral visions and lucid dreams. The astral travel of Saint Frances into the Christian hell was most likely heavily influenced by Dante's Inferno, which itself is very like an astral voyage in many respects, including the presence of a psychopompic spirit guide. 

Emmanuel Swedenborg

After the Protestant "Reformation," the Church began to lose its stranglehold over the priestcraft's alleged intermediary role between the earthly and spiritual realms, and more accounts of astral projection began to be openly recorded. In the 1700s the Swedish scientist Emanuel Swedenborg experienced astral projection and astral visions on a regular basis. Swedenborg wrote a huge number of books describing his voyages into heavens and hells and his communion with spirits and angels. He used these experiences as the basis for a new branch of mystical Christianity, which he founded in London.

Similar to the Hermeticists that preceded him and the astral travellers of later eras, Swedenborg wrote that there were actually multiple higher and lower levels of both heavens and hells. He also indicated that spirits are intermediaries between humanity and the Divine, but prudently warned against believing everything that the spirits say since they often did not tell the truth.

Swedenborg distinguished between the experience of projection out of the body and the experience of Mind's Eye visions (travelling "in the spirit") — describing how on some occasions he would remain aware of his physical body but travel into the realms of the spirits and angels within the vision, but could still converse and interact with them. Swedenborg gave an excellent  description of projection from the liminal deep theta trance state on the threshold of sleep, which he called "being taken out of the body." 

As Swedenborg wrote: "The man is brought into a certain state which is intermediate between sleep and wakefulness. While he is in this state he cannot know but that he is quite awake; all the senses are as much awake as in the completest state of bodily vigilance, the sight as well as the hearing, and what is remarkable, the touch, which is then more exquisite than it can ever be in bodily wakefulness. In this state spirits and angels have been seen exactly to the life, and also heard, and what is amazing, touched; and almost nothing of the body then intervenes."

William Blake and the Angels 

A generation after Swedenborg, William Blake also had extensive astral visions and journeys into astral dimensions related to Christian mythology. Blake once witnessed a phantom procession of ancient monks in Westminster Abbey, and he was visited by spirits (angels) so often in his own quarters that he persuaded some of them to sit for portraits. Blake commented that most of his poetry was effortlessly received from the angels and was only transcribed by himself.

Once the voice of a spirit claiming to be the archangel Gabriel spoke to Blake and requested to sit for one of these portraits. Blake was suspicious that the spirit might have been lying about its identity, but the spirit told him that he would have "good assurance." As Blake recounted : "I looked whence the voice came, and was then aware of a shining shape, with bright wings, who diffused much light. As I looked, the shape dilated more and more: he waved his hands; the roof of my study opened; he ascended into heaven; he stood in the sun, and beckoning to me, moved the universe. An angel of evil could not have done that—it was the arch-angel Gabriel."

Like Swedenborg, Blake believed the angels had chosen him to bring God's teachings to the rest of humanity, and he and his wife later joined Swedenborg's Church. Blake's dedication to pursuing his astral visions was commented on his wife, who told a friend: ""I have very little of Mr. Blake's company; he is always in Paradise."