One of the most basic issues in the discussion on the atonement is whether the atonement is objective or subjective. This is one of the first questions we must answer in the course of formulating a theology of the atonement.
If the atonement was subjective, Christ's atoning work was primarily "exemplary" or "revelatory." Christ's atoning work and death on the cross was an example of a holy life, or a special revelation of God's character. In this view of the atonement, Christ's example of a perfect life spurs us on to emulate him, or the ultimate revelation of God's character in Christ's innocent death allows us to comprehend God's love for us and respond in contrition and gratitude. These are subjective atonement theories because humanity is the subject of the atoning work--it is not, in fact, what Jesus did that reconciles us to God, but instead our action in response to his example. Those who respond to the cross in the way God desires are in actuality the ones doing the atoning, while the work of Christ is secondary.
If the atonement was objective, Christ's atoning work was in fact his own work; it is something that he did that reconciles us to God. Whether it was defeating the powers of evil, paying a ransom for our spiritual release or suffering the wrath of God, it is Jesus Christ's work that atones for us. This is called the objective view because it affirms the work of Christ is effectual for us, the objects of the atonement. Christus Victor, ransom theory, governmental theory and penal substitution are all objective theories of the atonement.
So which is it to be? In Christian history the idea of an objective atonement has been far more prevalent than the idea of a subjective one. Indeed, the Bible seems to give far more support to an objective view. According to 2 Corinthians 5, it is God "who reconciled us to himself through Christ...that is, in Christ God was reconciling the world to himself" (18,19). It was Christ who "redeemed us from the curse of the law" (Galatians 3:13); in his own flesh he was "putting to death that hostility [of the law] through it [the cross]" (Ephesians 2:16); "He saved us" (Titus 3:5).
The question of objective or subjective atonement is also the question of mankind's fundamental problem. A subjective view of the atonement downplays the significance of sin in our lives and essentially puts the work of atonement in human hands, an idea that the Bible strongly repudiates. In the subjective view, it is our mindset or our worldview or our beliefs that is the problem. In contrast, the objective view takes the answer to sin out of our grasp as humans and places it in the hands of God alone. In an objective view, nothing we can do can untangle us from sin; only God's action can save us. I think it is clear from the Bible that it is God's power alone that can save us, and any subjective view of the atonement is thus inadequate.
Once we affirm an objective atonement, we are free include subjective elements--for instance, the idea that Christ's atoning work was exemplary or revelatory. In fact, the Bible is clear on this very point: see 1 Peter 2:21 ("For to this you have been called, because Christ also suffered for you, leaving you an example, so that you should follow in his steps") and John 13:19 ("I tell you this now, before it [my death] occurs, so that when it does occur, you may believe that I am he"). However, while Christ's work provides an example and a revelation for us, they cannot cause or enable us to atone for ourselves. God does not reveal himself to effect atonement, but Christ's work in atonement still reveals God.
When we accept an objective view, however, another question arises. Is God also an object? According to penal substitution theory, yes. God's attitude toward human beings is conflicted; he loves his creation deeply, but he cannot allow sin to go unpunished. Thus not only must humans be made right with God, God must be made right with humans: a quality of his own attitude must be altered. Proponents of other theories, especially ransom theory, disagree, denying that God's must be reconciled to humans.
This is not a question I feel ready to answer. God as an object of atonement is the central idea of penal substitution, and provides a simpler explanation of Christ's work. That is, if God is the subject of atonement and humans the object, it is not easy to determine what, exactly, Christ's work accomplished. Proposing God as the object connects atonement to a known factor such as God's wrath against human sin or our debt to his honor. However, positing God as both subject and object of atonement seems to wrongly divide God's nature, pitting Christ (subject) against God (object). Any thoughts?