The Hate Merchant — Niven Busch

Caspar Damion Splane, pitchman extraordinaire, had a voice so compelling that no one could pass within earshot without looking to see what kind of man was talking. He could sell anything. At a time when nylon stockings were impossible to find and very expensive, Caspar popped open his sample case, hawked silk rejects as the real McCoy, and sold them all in one afternoon. His power over people became an obsession, a tool for control and power, a compensation for years of loneliness and suffering.
At the Kinderwall Sunshine Mission, revivalist Ma Kinderwall saves souls and feeds the poor from her soup kitchen. Followers flock to hear her. She has a gift, they say. During a down and out period of Caspar Splane's life, he and the Sunshine Mission collide, and in no time at all, he discovers a new audience for his madness. He adds “reverend” to his name and turns Ma's audience inside out. In the guise of selling peace, he grows rich on selling hate.
Published in 1953, The Hate Merchant, is a timeless and unforgettable account of the power of manipulation and the tragedies that result when rhetoric, slanted facts, suggestions of secrecy, and imagined threats are unleashed into the world unchallenged and unchecked.