I firmly believe that casual reading should be as stimulating as it is entertaining. Many of these are available at second-hand websites such as thriftbooks.com. There is also an innumerable amount of rare religious works available for free and entirely digitized here. I highly recommend you delve into the following books, which have made their way onto my shelf:
Drawing Down the Moon: Witches, Druids, Goddess-Worshippers, and Other Pagans in America by Margot Adler
Black Elk's the Sacred Pipe edited and published by Brown
The Ramayana (William Buck has a great translation/consolidation... but if anyone knows where I can get the entire epic translated line by line I would be incredibly grateful)
The Second Sex by Simone de Beauvoir
The Denial of Death by Ernest Becker
Ancient Mystery Cults by Walter Burkert
The Temptation to Exist and A Short History of Decay both by E. M. Cioran
Masochism: A Jungian View by Lyn Cowan
The Encyclopedia of Herbal Medicine by Andrew Chevallier
Gods of Love & Ecstasy: the Traditions of Shiva & Dionysus by Alain Danielou
Dionysos at Large by Marcel Detienne
The Serpent and the Rainbow by Wade Davis
Sayings and Anecdotes by Diogenes
The Greeks and the Irrational by E. R. Dodds
A Psychoanalytic Study of the Myth of Dionysus and Apollo by Dr Helene Deutsch M. D.
Women Who Run with the Wolves by Dr Clarissa Pinkola Estes, PhD (absolutely stunning piece)
The Evil Eye: An Account of this Ancient and Widespread Superstition by Frederick Thomas Ellsworthy
Living with a Wild God by Barbara Ehrenreich
The Secret History of Hermes Transmegistus: Hermeticism from Ancient to Modern Times by Florian Ebeling (the one I have is translated by David Lorton)
Caring for the Dying: A Doula Approach to a Meaningful Death by Henry Fersko-Weiss
Man into Wolf: An Anthropological Interpretation of Sadism, Masochism & Lycanthropy by Dr Robert Eisler Ph.D
The Tibetan Book of the Dead W. Y. Evans-Wentz (note, this is really best seen as an interpretation, and as an interesting landmark in literature, less than a definitive translation of a religious text, do read alongside the next two books...)
The Tibetan Book of Living and Dying: Revised and Updated Edition by Rinpoche Sogyal
Luminous Emptiness: understanding the Tibetan Book of the dead by Francesca Fremantle
Buddhist Thought and Applied Psychological Research: Transcending the Boundaries study by Germano, David F.; Waldron, William S.; Edited: Nauriyal, D K; Drummond, Michael S; Lal, Y B (I'll have another page eventually just for all of the studies I've been reading that I find especially fascinating, but this one is just too good not to recommend here)
The Haitian Vodou Handbook: Protocols for Living with the Lwa by Kenaz Filan (Houngan Coquille du Mer)
Church, State and Society 1760-1850 by William Gibson
Adventures in Immortality by George Gallup Jr.
Hereditary Witchcraft by Raven Grimassi
The Meaning of Witchcraft by Gerald B. Gardner (highly recommended for anyone interested in the history of modern wiccanism ISBN 978-1-57863-309-8)
Gardnerian Book of Shadows by Gerald B. Gardiner uploaded completely free here (the complete Ardanes, or bylaws and guiding customs, of Gardner's wiccan order)
Ecstacy, Ritual and Alternate Reality: Religion in a Pluralistic World by Felicitas D. Goodman
The King of the Ants by Zbigniew Herbert
Sacred Kink: The Eightfold Path of BDSM and Beyond by Lee Harrington
Human Sacrifice in Ancient Greece by Dennis Hughes (one of the lovely books I find use for again and again)
Modern Wicca: A History from Gerald Gardner to the Present by Michael Howard
On Desire: Why We Want What We Want by William B. Irvine
The Voice of Rolling Thunder by Jones & Stanley Krippner
Essays on a Science of Mythology: The Myth of the Divine Child and the Mysteries of Eleusis by C. G. Jung & C. Kerenyi (translator; Hull, R.F.C.)
When Breath Becomes Air by Paul Kalanithi
The Guru Papers: Masks of Authoritarian Power by Joel Kramer & Diana Alstad
The Imitation of Christ by Thomas á Kempis (there's a great translation by Leo Sherley-Price)
The History of Death: Burial Customs and Funeral Rites From the Ancient World to Modern Times by Michael Kerrigan
Dionysos: Archetypal Image of Indestructible Life by Carl Kerenyi
Witchcraft in Europe 400-1700 A Documented History by Alan Charles Kors & Edward Peters
On Death and Dying by Kubler-Ross
Etruscan Roman Remains in Popular Tradition and The Algonquin Legends of New England or Myths and Folk Lore of the Micmac, Passamaquoddy, and Penobscot Tribes both by Charles G. Leland
Grist for the Mill by Ram Dass
Children’s Conceptions of Death by Dr Richard Lonetto PhD
Medical Botany by Walter H. Lewis & Memory P.F. Elvin-Lewis
The Witch-Hunt in Early Modern Europe by Brian P. Levack
Mere Christianity by C.S. Lewis
The Ancient Mysteries: A Sourcebook, Sacred Texts of the Mystery Religions of the Ancient Mediterranean World by Marvin W. Meyer
The Shadow of Dionysus: A Contribution to the Sociology of the Orgy by Michel Maffesoli
The Book of Kells collected & transcribed by Bernard Meehan
Living in the Face of Death by Glenn H Mullin
Myths and Legends of India and South Seas Myths and Legends both by Donald A Mackenzie
Masochism: The Art of Power by Nick Mansfield
The Birth of Tragedy and Beyond Good and Evil both by Friedrich Nietzsche
Where the Chill Came From by Norman
Satan's Silence by Debbie Nathan & Michael Snedker
Black Elk Speaks by Neihardt
Dionysus: Myth and Cult by Walter F. Otto
The Complete Medicinal Herbal by Penelope Ody
Pagans: The End of Traditional Religion and the Rise of Christianity by James J. O’Donnell
Strange Histories: The Trial of the Pig, the Walking Dead and Other Matters of Fact From the Medieval & Renaissance Worlds by Darren Oldridge
Funeral Customs by Bertram S. Puckle (the entirety of this text is available online here)
The Joy of Suffering: Psychoanalytic Theory and Therapy of Masochism by Shirley Panken
A Defence of Masochism by Anita Phillips
Pagan Grace: Dionysos, Hermes, and Goddess Memory in Daily Life by Ginette Paris
The Adorers of Dionysos by James Morgan Pryse
The Quar'an (Penguin publishes a simple edition of the text cheaply through Amazon if you are having trouble getting ahold of it in a library or bookstore)
Fire in the Dragon a collection of psychoanalytic essays on folklore by Roheim
The Nag Hammadi Library edited by James M Robinson
Tyler's Herbs of Choice by Robbers & Tyler
The Oral Tradition from Zhang-Zhung by John Myrdhin Reynolds (a tad difficult to find, ISBN 99946-644-4-1)
Ordo Templi Orientis by Clyde Staude
Medieval & Early Renaissance Medicine: An Introduction to Knowledge and Practice by Nancy G. Siraisi
Start The Conversation: The Book About Death You Were Hoping to Find by Ganga Stone
The Botany and Chemistry of Hallucinogens by Dr Richard Evans Schultes PhD, MH & Dr Albert Hofmann PhD, Dr Pharm. HC, Dr Sc.Nat. HC (an extremely enjoyable read on its own---more like a journal of stories than a "dry text book" has any right to dream of being)
Shiva: The Wild God of Power and Ecstacy by Dr Wolf-Dieter Storl, Ph. D.
Children of the New Age by Steven J. Sutcliffe
Shambhala: The Sacred Path of the Warrior by Chongyam Trungpa
The Coolest way to Kill Yourself by Nicolas Tannic
Satanic Panic: The Creation of a Contemporary Legend by Jeffery S. Victor
The Important Examination of The Holy Scriptures by Voltaire
Anarchy or Chaos by George Woodcock
Anarchism by George Woodcock