Better stated would be if you kill your enemy, sin wins.
“But I say to you who hear: Love your enemies, do good to those who hate you, bless those who curse you, and pray for those who spitefully use you...But if you love those who love you, what credit is that to you? For even sinners love those who love them."
"Bless those who persecute you; bless and do not curse. Rejoice with those who rejoice, and weep with those who weep...Repay no one evil for evil. Have regard for good things in the sight of all men. If it is possible, as much as depends on you, live peaceably with all men. Beloved, do not avenge yourselves, but rather give place to wrath; for it is written, 'Vengeance is Mine, I will repay,' says the Lord."