And Seven Times Never Kill Man
by George R.R. Martin

The story of a trader in alien artifacts named neKrol who lives on a planet inhabited by a peaceful and enigmatic non-human race called the Jaenshi. They worship mysterious pyramids they build their settlements around.
    The peace is shattered by the arrival of a militaristic religious cult known as the Steel Angels, who worship a god called Bakkalon. These zealots begin to claim increasingly large sections of the alien’s land as they try to colonize the planet.
     Meanwhile, the trader tries to organize the aliens to fight back, but they seem largely indifferent to the threat.

"The ending is freaking crazy and scary, leaving a lot to interpretation.