"I don't care if it rains or freezes, long's I got my Alien Jesus...
Some of us will remember A Case of Conscience, by James Blish, as well as Jesus on Mars, by Philip Jose Farmer.
There are other books, I'll bet, which explore whether or not the appearance of a seemingly-divine saviour is unique to Earth and humans... Those are just the only ones I can think of. Mind you, the appearance of a divine saviour remains fiction to most of the current inhabitants of Earth, too...
On the other hand, there's Crazy Eddie (cf. The Mote in God's Eye).
