The Debt Is Paid in Full

Tetelestai was an accounting word in Biblical times. We were in debt—a debt we could not pay. We were way over our heads, indebted because of our sin, imprisoned by our sin. But Tetelestai means the debt is paid. The debt is paid!
In the ancient world, when someone was put in prison, they would write their offenses on a piece of paper and place it on the doorpost where that person was incarcerated. When the sentence was completed and the time was served, they would take down the sign and write across it: “Tetelestai! Paid in full!”
Jesus paid the debt that He did not owe because we owed a debt we could never have paid. He lived a life we could not live and died a death we deserved in order that we might have eternal life. Because of the cross, as God reached out His arms to us, Jesus is saying, “I love you this much.” The holiness of God and the mercy of God intersect in the person of Jesus.
This is why salvation is finished. There’s nothing you can add to it. If you try to add anything—your penance, your prayers, your self-punishment, your good deeds, your own good works—you only distort it! It’s the pure and perfected love of Jesus Christ. There’s only one thing perfect in this world: the perfect love of God in Jesus Christ! Tetelestai!