The God Engines by John Scalzi, 136 pages
This novella is short, brutal, and I didn't see the end coming.
In this story, gods not only exist; they are powerful and war with rival gods. The defeated gods are enslaved and forced to be living engines for the starships of the faithful--humans who worship the conquering god. The captured gods begin to rebel, Captain Ean Tephe realizes the problem is bigger than he ever imagined.
