“hey ducky pal... our true enemy isnt even people. its the devil.”
You cannot take the condition of the human heart out of your equation. The Devil can’t make us do anything.
The heart is deceitful above all things and beyond cure. Who can understand it?
Well, God can understand it! And did something that Jeremiah didn’t know about yet... died on a cross to save it. That’s the point.
The gospel imbues the deep believer with a new energy. An energy that seeks FIRST to pull the sinner from the grip of sin, and comes on with unusual weapons of love and kindness as well as rebukes that are focused at evil and which do not constitute broadside damnations of people. If the need arises to protect one’s community from deadly danger it can use the sword but that is not the first choice and it is never selfish — a martyrdom is preferred to selfish warfare. Quite a different tune than the world sings.
Basically... the Old Testament is God’s elementary school. Its lessons never become false within their domain, but they are not the complete picture any more than elementary school lessons would constitute college coursework.