The atonement debates seem to be heating up again. Much of the ground has been thoroughly covered, but perhaps a few comments might be productive.
First, what is the nature of the fall? It is first of all a loss of faith in God, and the rest follows. The serpent is portrayed as preaching doubt in God: distrust of God's honesty, distrust of God's motives, distrust of God's word. The fall happens when we say in our doubt, "That's right; I can't trust God. He doesn't have our best interests at heart. He's trying to keep us down. He's trying to keep exaltation for himself." It is precisely a loss of faith -- a loss of trust in God -- that is the key moment of humanity's fall from grace. Grace, again, is a good relationship with God. When our actions advertise a distrust of God, when we say with our actions "God is not trustworthy", implicitly accusing God either of duplicity and treachery or of a lack of wisdom -- this inherently and by its very nature destroys the relationship of grace.
If the fall is a loss of faith -- loss of trust in God -- then is righteousness anything other than faith? Is righteousness anything other than confessing, "God is trustworthy"? Is a return to our right minds any more complicated than that realization that God is trustworthy, that he is for us and that his word can be trusted? God's faithfulness is the bedrock on which our faith stands. And our trust is not a blind leap or an irrational one, but a reliance on the reality of God's trustworthiness.
Abraham and the ancients were reckoned righteous by faith, because they considered that God who made the promise was faithful.
What about our faith? As guilty people, we dare not trust the judge. Does God have our best interests at heart? That question becomes, in our bad consciences, whether the judge has at heart the best interests of the guilty. We dare not risk it, so we hurry to accuse the judge of unfairness, to create a cosmic mistrial, to get ourselves acquitted not by innocence but by counter-accusations. That is unbelief. Notice how atheism -- supposedly a belief that there is no God -- actually in practice is much more preoccupied with accusing the judge of unfairness. The driving force of atheism is the variety of unbelief spoken of in the fall -- unbelief in God's fairness -- rather than unbelief in God's existence. The innocent may go before a judge boldly, but not the guilty.
Here is one place where Christ speaks plainly and clearly to us. It is in Christ that God has proved his faithfulness to us. In Christ, God has shown the world that he has our best interests at heart, even as guilty as we are. It is in seeing Christ and hearing the message of Christ that we trust God again.
And as we trust God again, we find that this is righteousness. This is faith; it comes through hearing the message of Christ. As we trust God again, we find that we are in a right relationship with him again, and that this is grace; it comes through Christ. The day of accusing God to justify ourselves is over.