One who holds a false religious belief; a misbeliever.
One not restrained by moral principles; an unscrupulous villain.
One who has behaved badly, or illegally.
Lacking in conscience or moral principles; unscrupulous.
Holding an incorrect religious belief.
One who believes dogmatically in something regardless of evidence or even conclusive proof that the thing is false or was staged; one who has true-believer syndrome.
Used other than figuratively or idiomatically: see true, believer.
A strict follower of a doctrine.