Psalm 18: 39 For you girded me with strength for the battle; you made my assailants sink under me. 40 You made my enemies turn their backs to me, and those who hated me I destroyed. 41 They cried for help, but there was no one to save them; they cried to the LORD, but he did not answer them. 

This is a continuation of King David’s psalm thanking God for giving him victory over his enemies. V.40 tells us David’s enemies were running away “my enemies turn their backs to me”. Did David and his army show any mercy? No. “They cried for help, but there was no one to save them”.

The contrast between the Old Testament approach to enemies (destroy them) and the New Testament approach (love them) is striking. It’s an amazing and even baffling reality to understand.