Of the last sayings of Christ on the cross, none is more important or more poignant than, “It is finished.” Found only in the Gospel of John, the Greek word translated “it is finished” is tetelestai, an accounting term that means “paid in full.” When Jesus uttered those words, He was declaring the debt owed to His Father was wiped away completely and forever. Not that Jesus wiped away any debt that He owed to the Father; rather, Jesus eliminated the debt owed by mankind—the debt of sin.
Just prior to His arrest by the Romans, Jesus prayed His last public prayer, asking the Father to glorify Him, just as Jesus had glorified the Father on earth, having “finished the work you have given me to do” (John 17:4). The work Jesus was sent to do was to “seek and save that which is lost” (Luke 19:10), to provide atonement for the sins of all who would ever believe in Him (Romans 3:23-25), and to reconcile sinful men to a holy God. “All this is from God, who reconciled us to himself through Christ and gave us the ministry of reconciliation: that God was reconciling the world to himself in Christ, not counting men’s sins against them. And he has committed to us the message of reconciliation” (2 Corinthians 5:18-19). None other but God in the flesh could accomplish such a task.
Also completed was the fulfillment of all Old Testament prophecies, symbols, and foreshadowings of the coming Messiah. From Genesis to Malachi, there are over 300 specific prophecies detailing the coming of the Anointed One, all fulfilled by Jesus. From the “seed” who would crush the serpent’s head (Genesis 3:15), to the Suffering Servant of Isaiah 53, to the prediction of the “messenger” of the Lord (John the Baptist) who would “prepare the way” for the Messiah, all prophecies of Jesus’ life, ministry, and death were fulfilled and finished at the cross.
Although the redemption of mankind is the most important finished task, many other things were finished at the cross. The sufferings Jesus endured while on the earth, and especially in His last hours, were at last over. God’s will for Jesus was accomplished in His perfect obedience to the Father (John 5:30; 6:38). Most importantly, the power of sin and Satan was finished. No longer would mankind have to suffer the “flaming arrows of the evil one” (Ephesians 6:16). By raising the “shield of faith” in the One who completed the work of redemption and salvation, we can, by faith, live as new creations in Christ. Jesus’ finished work on the cross was the beginning of new life for all who were once “dead in trespasses and sins” but who are now made “alive with Christ” (Ephesians 2:1, 5).
article source: What did Jesus mean when He said, “It is finished”? | GotQuestions.org