Lord of Light
A colony of humankind is subjugated by the First Colonists, the crew of the starship that brought them to their new home 1000 years before. They have taken control of ancient technologies and enhanced themselves with godlike psychic powers and virtual immortality. Adopting the panoply of the venerable Hindu religion, they live lives as its Gods, surrounded by advanced technology within the trappings of a primitive civilization.

Our hero Sam, unready to battle the tyrannical forces of the Celestial City allied with his former wife, now the rapturous Kali, Goddess of Destruction.  A story of the classic drama of power, love, honor, pride, and fantasy erupting in an epic war of the Gods and ultimate transcendence.
Fiction, Hindu Gods, Hugo Award Winner, Space colonies, award:hugo_award=1968
Roger Zelazny