Before I became a Christian, when my mind and religious thoughts were tohu wa bohu, I had a decent collection of the works of other religions, the occult, etc. Just off the top of my head (as that was nine years or so ago):
1) Black Elk Speaks
2) Random other Lakota books (two by Wallace Black Elk)
3) John Fire Lame Deer's book
4) Archie Fire Lame Deer's book
5) Leonard Crow Dog's book
6) Others I can't remember
7) A large book of Navajo sand drawings and myths
8) God is Red by Vine Deloria (if that counts)
9) The Poetic Edda
10) Teutonic Magic by Kveldulf Gundarsson
11) Teutonic Religion by Kveldulf Gundarsson
12) RuneLore by Edred Thorrson
13) Futhark by Edred Thorsson
14) The Book of Ogham by Edred Thorsson
15) The Egyptian Book of the Dead, E.A. Wallis-Budge translation
16) The Bardo Thodol, W.Y. Evans-Wentz translation
17) The Fairy Faith in Celtic Countries, by W.Y. Evans-Wentz
18) The Qur'an
19) Mad Bear
20) Rolling Thunder
21) Book of the Hopi by Frank Waters
22) The Rg Veda
23) The Upanishads
24) The Bhagavad-Gita
25) Others I can't remember at the moment.
26) Others that I looked at with religious fervor, namely, Nietzsche, as well as writings and poems and interviews of those I idolized, e.g., Jerry Garcia, Ginsberg, Ken Kesey, etc.
All of those prepared me for the absolute bottom, which was William Burroughs. His writings were like a Bible to me for a year and a half of my life, and I can honestly say that I have never encountered a darker mind, or darker works, than his. When I think about "doctrines of demons", I think of his works, and the utter destruction of goodness and beauty and truth, indeed, even of language itself, found therein.
The sheer reality of the demonic has never been more apparent to me than in the works of William Burroughs. My mind and heart were slaughtered in him, if they weren't already. How I could have managed to see him and his writings as a means of enlightenment, and not as the filthy, life-destroying darkness that they were, amazes me.
When I was saved in 1999 I drove to our church parking lot with my father and tossed the whole lot of them into the dumpster, ripping up a couple for good measure, as well as hundreds of dollars worth of anti-Christian, blasphemous c.d.'s. In retrospect I wish I would have torched them all, just so they could never even possibly end up in the hands of other people.
God has done so much for me, and I have given Him such a poor return on His investment. And that's not humble piety, that's the sad reality.
If ever anyone did good by me, it was certainly Him.