Here are some of the books that I found inspiring as a child, and some that I have discovered since.
Illustrated books for younger children
The Little Prince by Antoine de Saint-Exupéry
Google Books · Wikipedia
The Whales' Song by Dyan Sheldon and Gary Blythe
It is presumably meant to be read aloud to small children, but it is enjoyable for all ages.
Amazon.co.uk · GoodReads
Where is God? by Lawrence and Karen KushnerB Keeper on Amazon.com says it all really:
Kushner's Where Is God is a wonderful introduction to the concept that God's presence infuses nature and all human exchanges and experiences. I actually prefer this board book to the full-size, older-children's book it is drawn from (Because Nothing Looks Like God), because the board book forces one to linger on the poetry of the text and the tenderness of the cropped illustrations. I get choked up almost every time I read this little book to my two-year-old son, simply because it is so simple and so true, and because I feel it expresses exactly my belief about God's immanance and the joys of being human here on earth.Lawrence Kushner is a Reform rabbi and currently the scholar-in-residence at Congregation Emanu-El in San Francisco, California.
Jonathan Livingston Seagull by Richard Bach
An absolute classic ever since it was published, Jonathan Livingston Seagull is the story of a gull who is not like other gulls. He lives to fly rather than to eat. Eventually he is shunned by the other gulls, until some come to learn from him. This is a story of individuality and courage, beautifully illustrated with pictures of gulls in flight.
People who make their own rules when they know they're right...people who get a special pleasure out of doing something well (even if only for themselves)...people who know there's more to this whole living thing than meets the eye: they'll be with Jonathan Seagull all the way. Others may simply escape into a delightful adventure about freedom and flight.
Longer books for older children
The Earthsea Quartet by Ursula Le Guin
Ged, a mage from a remote island, goes to wizard school on Roke, but one day when he is showing off his powers to the other students, he brings a terrible thing into the world: a gebbeth. He must go on a quest to track it down. On his journey, he has wonderful adventures and meets a dragon and an unhappy priestess.
Amazon.co.uk · Fantasy Book Review · Ursula K Le Guin
Witch Child by Celia Rees
"compelling and convincing.Rees has become a major writer for teenage readers." Independent
"every now and then one reads a book which stirs up the deepest of feelings and continues to cause ripples and this book is just such a one" School Librarian JournalAmazon.co.uk · Celia Rees
The Secret Life of Bees by Sue Monk Kidd
This novel has also been made into a film directed by Gina Prince-Bythewood.
Amazon.co.uk · Sue Monk Kidd