The following is a quote from Marcus Borg. Even though I don't share his beliefs about God I think its a very insightful quote.
"The fifth [interpretation of the cross] is the familiar sacrificial understanding of Jesus' death: 'Jesus died for our sins'. Though its ingredients are in the New Testament, its full development did not occur until about nine hundred years ago. Yet it is the most emphasized in popular Christianity and is central to the earlier paradigm. In its developed form, it sees the story of Jesus primarily within the framework of sin, guilt, and forgiveness. We have all sinned against God and are guilty. Our sins can be forgiven only if adequate sacrifice is made. The sacrifice of animals does not accomplish this, nor can the sacrifice of an imperfect human (for such a person would simply be dying for his or her own sins). Thus God provides the perfect sacrifice in the form of the perfect human, Jesus. Now forgiveness is possible, but only for those who believe that Jesus died for our sins.
If taken literally, all of this is very strange. It implies a limitation on God's power to forgive; namely, God can forgive only if adequate sacrifice is made. It implies that Jesus' death on the cross was necessary - not just the consequence of what he was doing, but that it had to happen, that it was part of God's plan of salvation. It also introduces a requirement into the very center of our life with God: knowing about and believing in Jesus and his sacrificial death.
But in it's first-century setting, the statement 'Jesus is the sacrifice for sin' had a quite different meaning. The 'home' of this language, the framework within which it makes sense, is the sacrificial system centered in the temple in Jerusalem. According to temple theology, certain kinds of sins and impurities could be dealt with only through sacrifice in the temple.
Temple theology thus claimed an institutional monopoly on the forgiveness of sins;
and because the forgiveness of sins was a prerequisite for entry into the presence of God, temple theology also claimed an institutional monopoly on access to God.
In this setting,
to affirm "Jesus is the sacrifice for sin" was to deny the temple's claim to have a monopoly on forgiveness and access to God. It was an anti-temple statement. Using the metaphor of sacrifice, it subverted the sacrificial system. It meant: God in Jesus has already provided the sacrifice and has thus taken care of whatever you think separates you from God; you have access to God apart from the temple and its system of sacrifice. It is a metaphor of radical grace, of amazing grace.
Thus 'Jesus died for our sins' was originally a subversive metaphor, not a literal description of either God's purpose or Jesus' vocation. It was a metaphorical proclamation of radical grace; and properly understood, it still is.
It is therefore ironic to realize that the religion that formed around Jesus would within four hundred years begin to claim for itself an institutional monopoly on grace and access to God." (The Heart of Christianity, page 94-95)
