There is a difference between religion and experiential spirituality.
Religion is ritual and myth and organization -- the outer vehicle of spiritual traditions.
Spirituality is exploring consciousness and subtle energies and feelings.
Many speculative fiction or scifi writers incorporate spiritual and/or psychic and/or religious themes in some way.
Spirituality and science don't have to conflict.
One can be spiritual and have a scientific worldview, even a secular worldview.
Spiritual inquiry and scientific inquiry are both based on observing the nature of reality. One can be systematic and compare experiences with previous statements or theories about reality. Or one can be pragmatic or playful or wild in exploring higher states.
Another category of scifi is the exploration of psychic phenomena and mental evolution, which overlaps with both religion and spirituality. This type of scifi bridges to spiritual scifi and can bride direclty to ones own spiritual inquiry.
See this website:
Science Fiction Featuring Various Specific Religions
To quote: "This document lists mainstream science fiction novels and stories in which specific real-world religious groups are prominently featured, usually through characters who are adherents and/or stories which take place in a setting with a dominant religion."
Some scifi writers transcend the genre, arguably creating enduring works of literature. Some of the best science fiction is "soft" scifi which tackles sociological issues, such as the Dispossessed and Left Hand of Darkness by Le Guin. Gibson's and others accounts of advanced artificial intelligence point to the development of higher and expanded states of consciousness.
Around age 15, reading both soft scifi and scifi with spiritual themes opened my mind to many possibilities for humanity.
Scifi inspirations were a big factor in my passion in my late teens and onward for exploring taoist, hindu and buddhist spiritual practices.
I have found these writers very inspiring at times: Le Guin, Heilein, Henderson, Silverbert, Zelazny, Bradley, Robinson, Card, etc.
Here is a reading list of some of my favorite scifi and fantasy reads that I made for a friend. A number of these contain spiritual themes:
* = a must read
*Left Hand of Darkness; Dispossessed; Earthsea Quartet, Ursula K. Leguin
*Diaspora, Greg Egan
*Stranger in a Strange Land; The Moon Is A Harsh Mistress; etc., Robert Heinlein
*Mars Series: Red Mars; Green Mars; and Blue Mars, Kim Stanley Robinson
*The Diamond Age; Snow Crash; Cryptonomicon, Neal Stephenson
*Neuromancer series, William Gibson
*Where Late the Sweet Birds Sang, Kate Wilhelm (to read: The Infinity Box and The Clewiston Test.)
*Pilgrimage: The Book of the People; Holding Wonder; etc., Zenna Henderson
*Son of Man; the Stochastic Man, by Robert Silverberg
*Lord of Light, by Roger Zelazny
*Forever Peace; Forever War, Joe Haldeman
*Flowers For Algernon, Daniel Keyes
*Stars in My Pocket Like Grains of Sand; Dhalgren, Samuel R. Delany
*1984, George Orwell
*Farenheit 451; The Martian Chronicles; etc., Ray Bradbury
*A Clockwork Orange, Anthony Burgess
*Brave New World, Aldous Huxley
*Do Androids Dream of Electric Sheep?; Ubik by Philip K. Dick
*Ender's Game series; Alvin the Maker series, by Orson Scott Card
*A Canticle for Leibowitz, Walter M. Miller Jr.
*Solaris, Stanislaw Lem
*Lord of the Rings trilogy, J.R.R. Tolkien
*Last and First Men, Stapledon, Olaf
*Smile on the Void, Stuart Gordon
*Childhood's End; 2001 series; etc., Arthur C. Clarke
Starseed trilogy, Spider Robinson
Watership Down; Shardik, Richard Adams
Darkover Series; The Mists of Avalon, Marion Zimmer Bradley
Startide/Uplift series, David Brin
Shockwave Rider, by John Brunner
Illuminatus triology, Robert Shea & Robert Anton Wilson
The Andromeda Strain; The Terminal Man, Michael Crichton
The Saga of Pliocene Exile series; Diamond Mask; Hyperion Series, Dan Simmons
Contact, Carl Sagan
Foundation triology, Asimov
Gateway series, Frederik Pohl
Dragonriders of Pern series, Anne McCaffrey
Ringworld series, Larry Niven
Perelandra series, C.S. Lewis
Dune series, Frank Herbert
Starchild triology, Jack Williamson