He had every right to kill him. All he had to do was use the knife in his hand.
David was God's newly anointed king even though David had not yet been coronated. And why? Someone else still sat on the throne.
That ‘someone else’ was King Saul.
You likely recall that God's people had once prayed for a king so that they could be like their worldly neighbors. Understandably taking offense at their desire to trust someone other than Him, God warns his people that they are asking for trouble. Having an earthly king will not solve their problems near as much as it will create them. But God answers their prayers, and King Saul gets off to a great start.
But the honeymoon ends when Saul becomes disobedient and loses God's favor. The prophet Samuel then anoints an unsuspecting shepherd boy, David, to take his place as king and both David and Saul share a path for an extended stretch of highway.
Saul, who has lost God's favor, is now losing his mind. Erratic, melancholy, and murderous, Saul is unraveling. An opportunity presents itself for David to end Saul's mad reign even as Saul and his men are trying to hunt him down.
In a plot twist, Saul finds himself in the same cave that David and his men are hiding. Saul does not see David as he stumbles into the cavern to relieve himself. David's men then whisper to their leader and say: "Here is the day of which the LORD said to you, 'I will give your enemy into your hand, and you shall do to him as it seems good to you.'" (1 Samuel 24:4)
David approaches his nemesis and raises his knife. But instead of plunging his blade into the king that has made his life miserable, he "stealthily cuts off a corner of Saul's cloak."
As Saul stumbles out of the cave and into the light, David turns to his men and says, "The LORD forbid that I should do this thing to my lord, the LORD's anointed, to raise my hand against him; for he is the LORD's anointed." So David scolded his men severely and did not permit them to attack Saul."
With a swatch of cloth from Saul's robe in his hand, David runs after the king.
"My lord the king!" David cries out.
David said to Saul, "Why do you listen to the words of those who say, 'David seeks to do you harm?' This very day your eyes have seen how the LORD gave you into my hand in the cave; some urged me to kill you, but I spared you. I said, 'I will not raise my hand against my lord; for he is the LORD's anointed.' See, my father, see the corner of your cloak in my hand; for by the fact that I cut off the corner of your cloak, and did not kill you, you may know for certain that there is no wrong or treason in my hands. I have not sinned against you, though you are hunting me to take my life."
Any expert in war or political strategist will say that the right thing to do at this moment is to kill one's adversary. Saul was there to kill David. God's newly anointed would have been justified in ending the life and reign of the madman who had lost God's favor. But he doesn't. Instead of squelching the threat that Saul represents, David chooses mercy. He chooses life even though death was deserved.
Ultimately, Saul's story does not end well. Both Saul and his son, Jonathan, are later killed in battle. David assumes the throne but does so while grieving all that Israel has lost. Vengeance belongs to God. It was not by David's hand that Saul's life ended.
In our modern experience, we frequently associate acts of mercy with weakness and capitulation. However, if we apply these same standards to God's repeated acts of mercy and kindness, we can only conclude that God, Himself, is feckless and soft. Indeed, God's Kingdom values are not the world's values.
What are the implications of such other-worldly, underserved acts of mercy? Reconciliation and shalom are the by-products of compassion and grace. Jesus's premiere teaching in the Sermon on the Mount details how agape love breaks the cycle of retribution that happens when we demand an eye for an eye and a tooth for a tooth. Mercy breaks the cycle of hurt and pain and provides opportunities for healing and wholeness.
Mercy is not simply an act reserved for the faithful in our churches. Acts of mercy--when discharged to our broader communities, the public sector, and yes, even the political machinations of a broken world--all convey a Gospel message far more faithful and powerful than any Ten Commandments that hangs on a courthouse wall can do.
It's God's mercy that gives us hope. It's our mercy to others that provides God's peace. It's mercy that reveals Christ's work in a world replete with violence and pain.