Magical mailman kills God in this novel of cosmic horror/occult ritual from Scott R. Jones, the author of Stonefish.

YOU ARE IN DANGER. You are afflicted with a mind parasite that feeds on your suffering and destroys your families so it can have something to drink from your ruined energetic body. To burn it out is the only way and it is the fire of your personal apocalypse, or revealing, that will perform this cleansing action. Contact me in any way you can should you require further help in this matter. I am here for you as a fellow human being, with a nervous system and feelings like yours, and as a practicing sorcerer, beyond feeling anything...