“Christ bore our sin. And he stripped Satan of the one weapon that he had that could damn us: namely, the valid accusation of our unforgiven sin. That weapon is taken from his hand. He is disarmed. We have no unforgiven sin. The blood of Jesus covers our sin — all of it. Therefore the cross was the decisive defeat of the condemning designs of the devil. He cannot succeed. The victory is ours though faith in Christ. This is why John said in Revelation 12:11, ‘They have conquered Satan by the blood of the Lamb.’ The blood of the Lamb strips Satan of his one condemning weapon, our unforgiven sin.
The god of this world is cast out of the courtroom. Our case is settled. Our judgment is passed. Our sins are forgiven. Our accuser has no records in his folder. He has no say in our future any more. We have passed from death to life. God has glorified himself by defeating his ancient adversary at the very moment when Satan thought he could win.”
— John Piper "For This Purpose I Have Come to This Hour"