The question of satisfaction is difficult and requires great sensitivity. This is true not only because Christ’s satisfaction lies at the heart of the Christian faith in all its dimensions (ecclesial, sacramental, theological, personal), but also because the intellectual problem of the atonement involves the intersection of several independent but similar logical structures (legal theory, grace, moral psychology, divine providence). In the following essay we will attempt to answer the following question with the help of Thomas Aquinas and Rik Van Nieuwenhove: What does it mean that Christ satisfied for our sins and why should his passion have satisfied for them?
In order to answer this question we need to begin with an understanding of sin. Satisfaction, after all, is somehow meant to alleviate the consequences of sin (more on that later). What is sin? Sin is, according to Augustine’s definition, “any word, deed, or desire contrary to the eternal law” (cf. ST Ia IIae q.71 a.6). Now, a human is capable of sin because he is free, and he is free because he has an intellect and will capable of comparing apprehended goods and selecting the best way to achieve his desire (cf. Ia IIae q.13 a.6). At the heart of man is one ultimate desire, which motivates every choice: the desire for happiness (Ia IIae q.1 a.7). And true happiness, as Aquinas tells us (Ia IIae q.3 a.8), is the attainment of that which is better than everything else: immediate knowledge of and participation in the divine life itself.
The will that drives a man is not an independent machine. Rather, it operates by incentives. The object of the will is the good understood (Ia q.82 a.4), and the will always follows the judgment of the intellect. It follows from this that our ability to desire perfectly the happiness for which we were created depends on the perfection of our understanding of that good: the richer this understanding, the fuller the desire. Now sin, as we said before, is an act of the person contrary to the eternal law, that is to say, an act of the person by which he deviates from the course set out in his nature (and paved by grace) toward the achievement of his ultimate goal. Since man was created in a state of natural perfection (Ia q.95 a.3) and grace (Ia q.95 a.1), God had readied the path for him into beatitude. But Adam, before he had followed that path to its divine conclusion, chose to deviate from it, and thus destroyed in himself the gifts by which his journey was possible in the first place. His mind, formerly perfect, was darkened. His will, originally set on God, was instead weakened and subject to the vagaries of his bodily passions. He did not have clear knowledge of his destiny and if he had, his will was ill-suited to direct him thither (cf. Ia IIae q.85 a.3).
This fallen state was transmitted from Adam to all his descendants (cf. Ia IIae q.81), sin was compounded upon sin through the generations. Man was disoriented, and in his lack of proper direction his offenses against God multiplied. Our creator, however, was gracious and had conspired to save us from sin and set us back in proper relation to Him. What was necessary for this?
In the ordinary notion of offense, the one who offends must pay the price for his crime, or the proper order of justice has not been restored (cf. IIa IIae q.62). In order for a thief to enter back into right relations with the one he has stolen from and the society of which both are members, restitution must be made. Now, someone else can make restitution for the thief out of generosity, or the thief can make payment himself, but the payment must be made. The question then is this: We sinners have offended God. We have, as it were, stolen from him the love and good works he deserved. Is there not some intrinsic law of the universe which makes it impossible for our relationship with Him to be restored until this debt is paid? (van Nieu 289)
There is something correct about this way of thinking. In sinning we do incur a debt, and a very great one. In acts of penance, our debt is paid back, and if we are incapable of making up the debt, perdition awaits. Justice does indeed enter into the consideration, and restitution is significant. However, the analogy is ultimately flawed. Why? In comparing God and sinner to victim and thief, we have presupposed some sort of absolute "law of the universe" to which God is subject (van Nieu 289). But God is subject to no law but his own nature, and his nature is personal, loving and merciful. Outside the context of a state, when the consideration is simply that one person has offended the other, the only thing absolutely necessary for the relationship to be restored is sorrow and love on the part of the transgressor, and mercy on the part of the one wronged. This sorrow and love can bear fruit in restitution, or the restitution could theoretically happen independently, without love, but in a relationship between persons not governed by some higher law, the vitality of the relationship depends primarily on the coordination of the wills of the persons involved, and not on the compensation for offense.
Let's translate these thoughts back onto the problem of sin. In sin, we do not know God as our destiny, and we do not desire Him as our highest good. This is wrong, and is a kind of theft that deprives God of the happiness for which he created us. We said that there are two ways of mending the relationship: restitution and conversion of heart. The extent of restitution depends not only on the thing taken but also on the dignity of the one offended. To deprive God of one's own perfection and happiness by mutilating and debasing oneself is a great crime, but this pales next to the consideration of our offending God in himself by detracting from the goodness he has laid out for us. It is impossible for me, in my damaged state, to pay the price for the perfection I have rejected: a car stolen and then wrecked could not be offered up as a replacement for what was originally taken. But even if we could pay condignly for the loss of ourselves, we can never compensate for the offense against God, which is infinite. So restitution is doubly impossible.
Likewise, conversion is impossible. We said earlier that sin darkens the intellect by leading it away from the truth and warping its judgment of the good. But without a clear intellect, it is impossible to know God as He is, as He calls us to himself. And without this knowledge, it is impossible to love him in a manner befitting his relationship to us. The intellect and will are the motors by which a person moves about in the world, aspires, and grows spiritually. Once these are damaged, they cannot heal themselves.
Before we proceed, notice another difference between the problem of sin and that of theft. In theft, the good that is violated is one of right and property. Prior to the crime there need not have been any relationship between victim and thief, and after restitution likewise. But in the relationship between God and man, the crime itself is a violation of that fellowship with God for which man was made, and so this is both essential to the restitution and to the restoration of the relationship. Without a real friendship with God, the problem of sin cannot be fixed.
We have established what distinguishes the problem of sin from other kinds of offense, and we have shown that the sinner can neither repay God nor restore the damaged bond. It follows that in order for man to be saved from paying for eternity a debt which, lacking charity, he can never satisfy, he needs grace to enlighten his mind and transform his will so that he can enter back into fellowship with God. Though this restoration does not in itself include restitution for sins committed, the dispensation of grace would be sufficient for man’s entry into beatitude.
God, however, is much greater than that. This personal God, who loves us enough to restore us, is also a God who brings forth the excellence in created things by mediating his blessings through them. And since it was the sin of man that brought death upon Adam's race, God ordained that through a man grace would be dispensed, and more marvelously still he chose (freely, without necessity) that humanity would be restored in such a way that its offenses were covered and its redemption merited in full. But none but God himself could cover the sins of all mankind, because while we were still sinners we were bound by the law of sin, which is spiritual death. So God became man, fashioned for himself from the flesh of a virgin a human body and breathed into it a human soul, and for a time the very being of the Eternal One walked among us clothed in our own nature. He taught us and healed us, and in accord with the divine plan, died for us to merit our salvation.
He died? But why should his death pay for our life? What good is it to die? To die is, in itself, nothing good at all. But remember what was said earlier: what was taken from God was the love and fellowship due to him. It was stolen through disobedience. Christ came to proclaim the truth, to give us light by which to see him, and to show us the path to him. All of these aspects of his mission are fulfilled in the cross. Christ's passion proclaims to us the profound love of God for humanity. By his obedience (cf. van Nieu 291) in an overwhelming spirit of charity (cf. ST IIIa q.48 a.2) he offers up to the Father something more precious than the price of all our guilt: Himself, the One and Only. But finally he shows us the way, the path of self-denial and abnegation (cf. van Nieu 286), by which the grip of worldly things upon the mind and will is loosened so that, enlivened by grace, they are free to turn back toward the excellence for whom they were made.
And so we see the utter perfection of Christ's satisfaction for our sins. The God-Man is the head from which flows all the grace necessary to sanctify and enliven His body. By virtue of his grace living in us we are capable, joined in his mystical body (van Nieu 290), of meriting our salvation and satisfying for our sins and those of others. But this is possible first of all because he satisfies the demands of justice, and his satisfaction is itself a demonstration of mercy, since our salvation could have been achieved by other means. Because this fulfillment of justice is so profoundly and visibly merciful, we cannot but encounter in Christ crucified the most wonderful image of God's love for us.