believe has 4 distinct synonyms spread across 2 of its 5 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is disbelieve.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
accept as true; take to be true
“I believed his report”
Synonyms, antonyms and the broader and narrower relations for believe come from Princeton University’s WordNet. Full sources and licences.
follow a credo; have a faith; be a believer
“When you hear his sermons, you will be able to believe, too”
credit with veracity
“You cannot believe this man”