Guilty of apostasy.
A person who has renounced a religion or faith.
One who, after having received sacred orders, renounces his clerical profession.
Not true to allegiance, duty, or vows
Lacking faith; lacking belief in something.
Unfaithful (said of people, towards their partners)
Not believing in God, religion, or a comparable ideology.
Serving to disappoint or deceive
Not observant of promises or covenants.