The Godmakers, Paperback/Frank Herbert

On the edge of a war-weary and devastated galaxy, charismatic Lewis Orne makes planetfall on Hamal. His assignment: to detect any signs of latent aggression in this planet's population. To his astonishment, he finds that his own latent extrasensory powers have suddenly blossomed, and he is invited to join the company of "gods" on this planet. And people place certain expectations on their gods....