Anyone commenting or preaching on these well-known verses better hesitate.
For preachers, at least in the Protestant world, these verses have become like clichés. How does one preach a cliché without always saying the same thing? We have heard these verses so often that they simply go in one ear and out the other. And yet, in these verses, Paul is rewriting, reformulating, reinterpreting tradition. Paul boldly seeks to understand what it means for all of us that Abraham was saved by faith and this faith is now also ours.
To begin with, Paul notes that we are all under the law. This is the first critical point and one that needs to be ever brought back to center stage. Western interpretation has, unfortunately, focused on a consequence (which Paul also mentions): since we are all under the law, we have all sinned, we are all sinners. Though this is a logical consequence, though it is correct to assert that we are all sinners, it is also note-worthy to recognize that Paul does not focus on that fact. He continually insists that we are all under the law.
This means, for Paul, that no one can reach God through her or his own merits, abilities, good conduct or works. No one can capture God. No one can reach God. It is precisely God who comes to us. We can name this inability to reach God "sin," but it is also much more. Yes, its consequence is sin, but its deeper reality asserts that even in the most beautiful of moments, even in the most intellectually or artistically stimulating moments, even in deeply spiritual insights, even in the most intimate love, we still have not reached perfection...and we will not, through any of those moments, reach God. This is what it means to be under the law. Every mouth is silenced. There is nothing that we can do. Through the law, we recognize this inability and then our sin as well (as we try to by-pass the law).
In contrast, Paul describes the righteousness of God, the righteousness that is given to us. This righteousness comes to us through faith in Jesus Christ. Is faith then a work? Is "believing" something we do? There is certainly a temptation to think that faith or believing is our work. This temptation is written within the text itself, but Paul excludes such an interpretation by what he has just previously established. Every mouth is silenced. Lips are sealed just as the tomb was sealed by a great stone. Nothing we can do will open the tomb, nothing will get us to God. No, the faith Paul writes about here is the faith of Jesus Christ. Jesus Christ is God's righteousness. It is this righteousness that creates faith in the first place. It is this righteousness, this person, Jesus Christ, who, as promise, awakens faith within us. Faith itself is a gift bestowed on us through the Holy Spirit, where and when the Holy Spirit wills.
What are we to make of Jesus Christ as "sacrifice of atonement"? Is our God a parent who sacrifices an only child? We are well aware of the stinging and justified critique that has been leveled at this notion of "sacrifice of atonement." It is one we need keep in mind, especially as preachers, since a metaphor describing God's action has far-reaching consequences in the faith and prayer life of believers. Metaphors of works produce more work! Metaphors of violence can too easily engender more violence.
The Gospel, however, is not about a God who is appeased by a sacrifice. It is not about a God who needs to be bargained with; many atonement theories, grounded in this idea of sacrifice, are simply guises for a ladder theology (we can still do something to get to God). As Gerhard Forde pointed out, these sacrificial theories incorporate God into human works, into human scheming.
The Gospel, however, is gift in a radical way: faith alone. I, you, have nothing that can get us to heaven so God comes to us and events faith in our heart. "By his blood..."--this is the radical nature of the gift of faith. It does not shy away from death itself. The "sacrifice of atonement by his blood" expresses the radical gift of the incarnation, albeit it in difficult words!
Luther is the first to acknowledge that Christ's death on the cross is better described as an execution (see his commentary on Psalm 111), and yet, he also acknowledges we continue to use the word sacrifice. To a certain degree, we are made responsible for this word. We are responsible for making this word understandable, approachable, for believers today. I think one way to do this has just been outlined: as the ultimate expression of God's radical and total involvement within creation and human history (as solidarity and not as appeasement or bargaining).
"He did this to show his righteousness..." God came not to show us what we have to still do, not show us a way to perfection (that is, sacrifice yourself -- it is good for you!). God came to reveal to us how great is the righteousness that is now given to us (verses 21-22), that now becomes ours as faith. We have here an instance perhaps of that other metaphor for atonement: the happy exchange. Christ takes everything that is ours and lays the burden on himself and gives us everything that is his. The gift of Christ's faith carries us. This gift imparts righteousness to us, makes of us believers, not through our work (for we are silent, we cannot boast!) but through the promise that Christ has accomplished all for us.