And yet, God commanded killing. An eye for an eye was sanctioned in the Old Testament. Jesus said to turn the other cheek but, what about the third time? There is actually a testament, Diogenese, where a people that literally followed that commandment were blessed such that their children could not be killed in combat and, yet, the children were needed for combat. Interesting eh? Is there anything you would kill for? Die for? The right of self defense even unto killing another has been long established even as killing has been generally condemned under law beginning with Thou shalt not kill. I think it began much earlier when God stayed the hand of Abraham or asked Cain what became of his brother.