In Jeremiah 21 the ones that were saved were strangely the ones who left the protection of the walls of the city and made themselves vulnerable by walking out and allowing themselves to "FALL" into the hands of their Chaldean enemies. Jeremiah 21:9. The people of Israel who remained behind the barriers of safety were destroyed. Jeremiah 21:7.
This is a picture of what it means to "present your bodies as a living sacrifice" (Rom 12:1) or to "take up the cross", a counter-intuitive way to live life (Jer 21:8) that means we give ourselves over seemingly unto death (death to self). We walk out into life's adverse situations dying to all means of self-protection and self-salvation trusting God. We are willing to be sheep amongst wolves and innocent as doves, but as wise as serpents.
This is the wisdom of God and surely not the wisdom of the world. 1 Cor 2.
It is victory through vulnerability.
Rom 12. We will see that God's strange way of vengeance is the cross. V19-21. His vengeance, that destroys evil, is to "overcome evil with good." This is the only way God or will ever destroy evil, thru the lifestyle of cross. See Matt 5:38-48;
The cross is God's vengeance against His enemies. Heb 2:14; 1 Cor 2:8. He has no other vengeance. His supreme acts of both vengeance and love always happen AT THE SAME TIME, at the cross. Jesus drew His enemies down into their own abyss by loving them to death.
Father forgive them. They know not what they do.