Though really sometimes, It can end up being far more effective to let God have his way with them.

Romans 12:19-21 Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord. Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head. Be not overcome of evil, but overcome evil with good.

Matthew 6:34 "Take therefore no thought for the morrow: for the morrow shall take thought for the things of itself. Sufficient unto the day is the evil thereof."

I recommend also reading the context in Matthew 6:24-34 for a beautiful scriptural "whitepill". Finally also:

Matt 10:28 "And fear not them which kill the body, but are not able to kill the soul: but rather fear him which is able to destroy both soul and body in hell.