Concise Oxford English Dictionary

BELIEF noun
1        an acceptance that something exists or is true, especially one without proof. A firmly held opinion or conviction. A religious conviction.
2        (belief in) trust or confidence in.

Phrases
        beyond belief astonishing; incredible.

BELIEVE verb
1        feel sure that (something) is true. Accept the statement of (someone) as true. Have religious faith.
2        (believe in) have faith in the truth or existence of.
3        (believe in) have confidence in.
4        think or suppose: I believe we've already met. (believe in) think that (something) is right or acceptable.