Oomphel in the Sky - H. Beam Piper

On the planet Kwannon, Terran colonists exploit the native Omphel people, using religion and superstition to maintain control. When a scientist begins to question the morality of this manipulation, tensions rise between truth and power. His efforts to reveal the deception threaten the fragile balance between conquerors and the conquered. The story explores themes of faith, colonialism, and the ethical limits of progress.