apostate
definition
a person who renounces a religious or political belief or principle
example
The community viewed him as an apostate after he publicly rejected the tenets of his faith.
synonyms
renegadetraitordefector
word origin — from the late Latin 'apostata', meaning 'deserter, runaway', which in turn comes from the Greek 'ἀποστάτης' (apostatēs), meaning 'deserter'.