According to substitutionary views of the atonement, Christ suffered a suffering that was due to us for our sins. Substitutionary views come in two varieties: (1) penal substitution views hold that Christ's suffering was a punishment of Christ for our sins; (2) non-penal substitution views hold that Christ was not punished but that nonetheless somehow his suffering was a substitute for our suffering. Pernal substitution views are, arguably, incoherent: y can only punish x for what y believes x to have done; anything else is an imposition of suffering, just or unjust, but not a penalty. It is difficult to figure out exactly how a non-penal substitution views would work, but there has been some recent work on this (Adam Pelser had some interesting ideas in a paper he presented at a recent SCP meeting, and I have recently read some good in-progress work from someone else).
In this post, I want to discuss how one can respond to a criticism (not an original one) that would apply equally to penal and non-penal substitutionary views. The criticism is that according to Christian doctrine, Christ's suffering redeemed us from eternal damnation. In other words, Christ's suffering must have been a sufficient substitute for eternal damnation. But while dying on the cross is very painful, people have suffered worse, and it seems likely that on orthodox views of hell as involving eternal physical pain, dying on the cross, even when one adds severe flogging beforehand, is not a sufficient substitute for an eternity in hell. And even if one adds the psychological suffering of being abandoned by most of one's friends, and maybe even bereft of God, to feel that suffering for less than twenty-four hours is not a sufficient substitute for an eternity of psychological suffering in hell—for, after all, orthodoxy holds that hell involves non-physical suffering as well. This is the "Insufficiency Criticism" (IC)—Christ didn't suffer enough for his suffering to substitute for our punishment.
One answer to this is to allow that the total suffering in hell is only finite, and that Christ's suffering during his passion might in fact have matched the greatest degree of deserved suffering in hell. But while it is possible for eternal suffering to be finite, it still seems likely, given what the Christian tradition has said about hell, that the suffering is very, very great in total, this is probably not the best response.
In response to the IC, I want to offer first a partial theory as to one aspect of Christ's spiritual suffering on the cross. According to Aristotle, the virtuous person enjoys doing virtuous activity. A virtuous person's emotions correctly track the truth of the matter: the virtuous person feels good about virtue and bad about vice. Now, I want to say something odd: if a perfectly virtuous person were to engage in a gravely vicious activity, she would find such engagement more spiritually painful than just about anything else that could happen. Of course, this is a per impossibile counterfactual. But I can justify it by pointing to three genuine possibilities. First, suppose that a presently virtuous person contemplates a past grave evil that she did and which evil has not yet been mended. This contemplation gives her great pain. Second, suppose that a presently virtuous person contemplates the fact that some presently virtuous people go on to become quite wicked over the years, and hence that she herself might do so. To the extent that she takes this thought emotionally seriously, she is deeply pained by the possibility of future vicious action. Third, recall that Aristotle says that a virtuous person enjoys the virtuous deeds of a friend, in a friendship of the best sort, as if they were her own, because the friend is another self. Now Aristotle thought one could only be a friend, in the best sense, of a virtuous person. Be that as it may, what he says about friendship can be said about love more generally, and it is possible to love a vicious person. And if a virtuous person loves a vicious, then the deeds of the vicious beloved can give the lover the kind of pain that they should give the beloved. These three cases should make clear the magnitude of spiritual pain it would be appropriate to feel at an evil action while one were committing it. After all, what would we not give not to be someone who had committed a murder, say?
Now, let us suppose that on the cross Christ, being not only a perfectly virtuous man but also God, is aware of all the evils ever done, fully understands the evil in its interpersonal and theological significance, and yet loves the evildoers. This makes it possible for him to feel the spiritual pain at the evil which the evildoer did not fully feel while doing the deed, a spiritual pain of immense magnitude. The offense was against the infinite God. Christ on the cross, on this theory, experiences that offense in its immense magnitude, and this suffering, though concentrated in time, is a sufficient substitution.
A difficulty with this theory is that one wonders why this substitutionary suffering had to be on the cross. After all, wouldn't Christ have felt the same spiritual pain earlier in his life, say while sipping wine at the end of a hard week's work and reflecting on the magnitude of evil? This theory does not do justice to the importance of the cross.
But I think we can bring the cross back to it. For Aristotle is not actually right in thinking that the virtuous person's emotions always correctly track reality. Emotions come and go. No matter how virtuous a person is, if she has been deprived of sleep for too many hours, whether by torturers or by parenthood, she will not have much in the way of appropriate emotions. She will, if she remains virtuous, act rightly, but may feel simply numb. A virtuous person's emotions correctly track reality only in circumstances which are appropriate for this tracking of reality. A virtuous person knows that parenting is a good, but she does not feel the warm glow of it except in appropriate observing conditions, typically ones incompatible with sleep deprivation, just as an art expert may not recognize the fake Rembrandt except in good light.
Now, Christ on the cross was, we might say, in ideal observing conditions in respect of evil. His emotions were genuinely human ones. Suffering has much to teach us experientially, which we may have already known theoretically. On the cross, as the perfectly innocent divine victim, he could humanly experience the fullness of the evils of the world, evils that he already divinely knew, and that he even theoretically already knew as a human being. Moreover, even if his physical pain did not have the same magnitude that the pain of someone being tortured to death over the period of a month might have had, the physical pain he did suffer was of sufficient magnitude to fuel an empathy that would humanly enable him to be spiritually pained at that victim's pain of being tortured over a month—or even at the physical pains of eternity in hell. He suffered, then, not just his own sufferings on the cross, but these sufferings of his own made it possible for him to suffer with the victims of all the past and future crimes he knew of, as well as to suffer, even more profoundly, with the perpetrators of these.
I do not think this exhausts what happened on the cross. In fact, I am very much unsatisfied with what I wrote. I don't even want to say that the theory I offer is true. But the availability of theories like this one shows that the IC should not be as persuasive as it initially seems.