I honestly had no idea where to put this thread. I debated between the LHP and the NeoPagan DIR; and it ultimately ended up here. If it is to be so, I'll ask a mod to move it.
Whether one believes in them or not, what are some books you recommend on subjects like monsters, myths, demons/demonology, magic(k), etc.? As well as ancient religions/civilizations?
There are several levels to this (as you began to outline in your post). First, the ancient world was swimming with beliefs about spirits and demons who influence inane and greater events, emotions, or circumstances. Near Eastern literature for example has a fine share of demons and monsters serving as antagonists. You can find this in Mesopotamian literature (for example in poems, stories, or in the central Babylonian creation mythos: The Enuma Elish which was recovered in the ruins of Nineveh in 1849), Egyptian literature, and in the traditions of many other important Near Eastern civilizations.
Enochian Jewish lore, also contains very descriptive details about fallen angels and the politics of a cosmic battle field. The Dead Sea Scrolls which were found in the Mid 20th century give us a unique insight into this world of duality.
As the centuries passed, and as Christianity marginalized various gods through out the Mediterranean and the Near East into demons, many Occult traditions developed and outlined hierarchies of angelic beings and infernal courts, and ways to connect with these forces. This include Christian and Jewish medieval mystical manuscripts, which also reincarnated in books published during the 19th century for a specific crowd. For example Waite's The Book of Black Magic, or the writings of French Magician and Occult writer Eliphas Levi. Books such as The Magus (written in the beginning of the 19th century by Francis Barrett) actually contained material which was collected from many books already existing for several centuries before this contemporary boom in Occult knowledge. Writers and Occultists which presaged the 19th century publishing include Agrippa and Binsefld (both of them active during the 16th century).
When you discuss Magick (with a K) we begin to explore the philosophies and traditions which Crowley presented us and which he inherited from the magical orders of the time, although taking them into new horizons. Crowley's library is pretty rich and not only includes magical work, but also novels which reflect his sentiments about the place of magic in the world, and his political position in this set.
Fiction wise. Much of what we recovered from the mysterious dark aspects of the ancient world were refined into horror fiction by writers such as Lovecraft who took the ancient Near Eastern literary world and built an elaborate universe of terrors from. Lovecraft did it so masterfully that there are people who incorporate his literature into their magical working.
You can actually trace academic writings about demonology in ancient civilizations and of course historical periods up to our times.
Here is an example of demonology in Egyptian literature:
Ancient Egyptian Demonology
Studies on the Boundaries between the Demonic and the Divine in Egyptian Magic
Written in the journal Orientalia Lovaniensia Analecta.
Ancient Egyptian Demonology