放下屠刀，立地成佛

to become a Buddha on the spot (idiom); instant rehabilitation; to repent and be absolved of one's crimes

to renounce evil and turn to virtue (idiom)

to mend one's ways (idiom); to turn over a new leaf

lit. to wash one's heart and renew one's face (idiom); to repent sincerely and mend one's mistaken ways; to turn over a new leaf

to give up evil and return to virtue

to repent and start afresh (idiom); to turn over a new leaf