Crucifixion was a common punishment for capital crimes in the first-century Roman Empire, and many individuals died on crosses at the hands of the imperial authorities. Jesus was not the only man ever crucified, yet His death by crucifixion atoned for sin. What made the death of Christ atoning when other deaths by crucifixion were not? The answer is that the death of Jesus atoned for sin because it was the death of the perfectly obedient God-man.
We cannot understand the significance of the death of Jesus without understanding how it is related to the kind of obedience He rendered to the Lord. Theologians typically distinguish between the active and passive obedience of Christ in explaining what the atonement accomplished. Let us start with the passive obedience of Jesus, which refers to the suffering of our Lord in our stead. The passive obedience of Jesus refers preeminently to His death on the cross, where He “bore our sins in his body on the tree,” receiving the punishment that we are due for our transgressions (1 Peter 2:24). However, His passive obedience is not limited to what He did on the cross. It includes all the suffering He experienced during the course of His earthly life. Born into this fallen world, Jesus experienced the consequences of sin on our bodies and relationships. He never sinned Himself, but Jesus nevertheless was subject to the trials of life under the sun. He was rejected by those who should have been His friends (Luke 4:16–30). He suffered the sorrow of seeing others die (John 11:28–35). By enduring the punishment for sin and the consequences of sin, Christ paid our debt of sin (Rom. 8:3).
If that were the only kind of obedience Jesus rendered to God, all He would have given us is a blank slate with respect to righteousness. We would no longer be unrighteous, but we would not have any righteousness, any record of obedience, either. Yet, eternal life is granted not to blank slates but to those who have a record of obeying the Lord. That is why we need the active obedience of Jesus as well. The active obedience of Jesus consists in His perfectly keeping every commandment given by God. By His active obedience, Jesus fulfills “all righteousness” (Matt. 3:15). His one act of obedience, referring collectively to the entire course of His life, secures life for His people (Rom. 5:12–21). When we trust in Jesus, this obedience is put on our record, and so we inherit eternal life (2 Cor. 5:21).