Small Gods by Terry Pratchett (1992)
Old but gold. Terry Pratchett's Small Gods is the thirteenth novel from his fictitious Discworld series. Discworld is an imagined world shaped like a giant disc balancing on the backs of four huge elephants that are standing on the back of an enormous turtle floating in space. Yup, this book will definitely drift you away from reality for a while. In Small Gods, you will get to see this world through the eyes of a god, who finds himself in the body of a tortoise. The novel is a satirical commentary on religion and its institutions without being, well, too preachy.
Available for $76 at swindonbooks.com