Used to emphasise a previous comment

(idiomatic, chiefly in the negative) To believe that something which one hears is truly the case.

Used to express astonishment or incredulity.

Alternative form of would you believe it

Alternative form of you'd better believe it

(idiomatic) You need to see something to believe it; visible facts cannot be denied. / (idiomatic) I am skeptical about your claim.

Used to ask whether the interlocutor believes in God.

Alternative form of believe one's eyes

To be amazed by what one sees.

(Britain, Ireland, sarcastic) Used to indicate that the speaker does not put faith in something they have just heard.