The phrase "be believed" refers to the act of being trusted or accepted as true by others. There are various synonyms that can be used to convey this meaning, including "be credible", "be trustworthy", "be reliable", "be convincing", "be plausible", "be accepted", "be acknowledged", "be authenticated", and "be confirmed". These synonyms not only express the same idea of being believed, but also provide alternative ways to convey the degree of trustworthiness in a particular context. Using synonyms can help writers and speakers to add variety and depth to their language, and to better convey their intended message to their audience.