Why did Jesus have to die on the cross? Why couldn't God, in his infinite mercy, simply say "I forgive you" to those he thought deserved forgiveness? In the answer to this question lies the doctrine of the atonement. The English word "atonement" refers to being "at one" (or reconciled) with God. Why was humanity estranged from God in the first place, how exactly did the reconciliation take place, and what does it mean for us today?
In his book Christus Victor, Gustaf Aulén outlines three main approaches to the atonement. According to the Classical View, which predominated from the second to the fourth century, sin is the byproduct of bondage to an evil supernatural being, the devil (1 John 3:8-10; 5:19). Human beings were originally created free moral agents, but the devil enslaved them and became the "prince of this world" (John 12:31; 16:8-11). In order to redeem mankind from slavery, God had to pay Christ as a ransom price. Dying on the cross, Jesus exchanged himself for humanity and became the devil's possession, but Christ was stronger than Satan and broke free from his bondage when he broke the bonds of death (Hebrews 2:14-15; Romans 6:6-10).
The Latin View developed from the fifth century through the Middle Ages. According to his view, God is holy and cannot by nature accept sin in his presence. Unless delivered from sin, humanity faces eternal estrangement from God, but since people are all sinful, no mere human sacrifice can meet the demands of divine justice. Motivated by love and mercy, God himself satisfies his own sense of justice by sending Christ as a sinless man to make the necessary sacrifice (1 John 2:1-2; 4:10). God as man propitiates himself, thereby demonstrating both his justice and his mercy (Romans 3:25-26).
The Pietistic View arose in the seventeenth and eighteenth centuries. According to this view, there was no literal ransom paid to the devil or complicated legal process of satisfying divine justice. Sin is a matter of the heart. People are sick with sin, and Christ came as a spiritual physician to heal humanity by calling for a new birth and by leaving a perfect example sealed by his selfless death. We are saved by becoming Christ-like in our moral lives. We know we are saved because we feel harmony and peace of mind.
Scripture uses poetic images and word pictures to explain the atonement: the lamb on the altar (propitiation), the relative who has fallen into slavery (redemption/ransom); the loving family (adoption), the estranged relationship (reconciliation), the battlefield (victory), the doctor's office (healing), the sheepfold under attack (rescue), and the law court (justification). Is one of these more theologically accurate, precise, or correct than the others? Are they all simply approximations or illustrations?
Some things are clear. The death of Jesus underscores the horror of sin and God's hatred for it. People are dying in sin and need a savior. Christ's atoning death incarnates God's love and mercy (Romans 5:8). Atonement is God's initiative from first to last (2 Corinthians 5:18-19). It is unthinkable to exploit God's love and loyalty by continuing to sin (Romans 6:1-2). Therefore, as redeemed people, we should live lives worthy of the Master whose name we now bear (Colossians 1:9-10; Ephesians 4:1-3).
Atonement is in the past; salvation is in the future. As we have been justified by his blood, so we will be saved by his life, that is, by his resurrected life when we, like him, are resurrected unto eternal life (Romans 5:9-10). God will preserve us from the devil unless we consciously rebel and return to the devil's bondage (Romans 8:37-39). These truths resonating within the hearts and minds of believers provide the purpose and motivation needed to live the ethical life.