Simon Kraft is the epitome of everything Charlie Eppes hates about the woolly thinking surrounding belief and those matters which he cannot pin down in a formula. Simon has seemingly boundless self-confidence and is providing information which pans out, which only makes matter worse.
Perhaps Simon's most egregious offense, however, is his complete respect for and tolerance of everything about Charlie, including his skepticism. Other irritants, like Marshall Penfield, can be severely ruffled, but Simon seems supremely oblivious to Charlie's palpable distaste for him.
In "Trouble in Chinatown", and as per his own prediction, Simon is mowed down by a hit-and-run driver.