There are several synonyms for the phrase "be afraid of" that can be used to add variety and depth to your writing. One alternative is "fear," which may be a more formal substitute. Other choices include "dread," which conveys a sense of intense apprehension, and "terrify," which implies an overwhelming feeling of fear. "Tremble at" or "quail before" can also be used to describe a sense of fear, while "cower from" implies an instinctive desire to hide from something that is truly frightening. Finally, "shy away from" is a softer synonym that suggests a reluctance to confront something that may cause fear or discomfort.