I think I'll hang back and listen to what others have to say, but may I first recommend this article on Spiritual Themes in Young Adult Boooks. It's not new by any means (published by ALAN in 1996), and the book lists are somewhat dated. Still, I think it's worth the read, if only because I believe authors should think carefully--and speak honestly-- about their intentions, when it comes to writing religion into their stories.*
Sneak peek:
"Because young adults are immersed in the psychosocial crisis of identity definition and are beginning to decide for themselves what they will ultimately believe in terms of spirituality, young adulthood is an opportune time to explore spirituality. It is an opportune time to learn about the myriad belief systems operating in our world, the young adult quest for spiritual knowledge, and the young adult process of identity definition in relation to spirituality. Many young adult books can provide the spiritual information young adults need to assuage the loneliness of their passage; some of the possibilities are presented here."
no subject
Sneak peek:
"Because young adults are immersed in the psychosocial crisis of identity definition and are beginning to decide for themselves what they will ultimately believe in terms of spirituality, young adulthood is an opportune time to explore spirituality. It is an opportune time to learn about the myriad belief systems operating in our world, the young adult quest for spiritual knowledge, and the young adult process of identity definition in relation to spirituality. Many young adult books can provide the spiritual information young adults need to assuage the loneliness of their passage; some of the possibilities are presented here."
http://scholar.lib.vt.edu/ejournals/ALAN/spring96/mendt.html
*ETA: I'm not by any means pointing a finger of accusation here...just making an observation.