Calque of the Latin use of crēdō (“believe”) with in plus accusative.
believe in (third-person singular simple present believes in, present participle believing in, simple past and past participle believed in)
- (transitive) To ascribe existence to.
- Do you believe in God? / the Easter Bunny? / ghosts?
- Since I don't believe in reincarnation, I believe that the only way to eliminate suffering is to die.
- (transitive) To believe that (something) is right or desirable.
- I don't believe in sex before marriage.
- I don't believe in making my bed.
- (transitive) To have confidence in the ability or power of.
- I believe in you, man! You can do it!
believe that something is right or desirable