E.C. Tubb 
Temple of Truth 
The Dumarest Saga Book 31

In relentless pursuit of Earl Dumarest come the emotionless minions of the Cyclan. Seeking the body-switching formula which would make them masters of the universe, they must seize Dumarest alive to gain his secret.It all comes together on the world of the Guardians, where in the great temple of their fanatical faith, the true co-ordinates of Earth are listed. There Dumarest will battle the Cyclan . . . while the fate of all humanity hangs in the balance.(First published 1985)