1. It is unjust.
According to this theory the one and only obstacle which stands in the way of the sinner's forgiveness is God's justice, and Christ's death has removed that obstacle by satisfying His justice. To this theory it is objected that, so far from being a triumph of justice, it is a triumph of injustice. It is doubly unjust—first, that God should not punish the guilty; and secondly, that He should punish the innocent. If the sinner deserves punishment, justice requires that he, and not another, should suffer. If Christ were perfectly innocent, justice requires that He should not suffer. There can be no justice, whatever else there may be, in punishing Him instead of the sinner. For what God's justice requires is surely not that where sin has been committed somebody should suffer, but that the sinner should suffer—he and no other (p. 101).
2. Jesus did not pay the penalty for sin.
He could not have suffered our penalty for sin, inasmuch as part, the largest part, of that penalty is remorse, which He could never have experienced. And, moreover, our penalty for sin is eternal death, and that He certainly has not suffered; while, on the other hand, the death He did die--namely, physical death--is not that from which He has delivered us, for we are all still subject to it. In no true or real sense, then, it is alleged, can Christ be said to have suffered the penalty that we incur by sin... (p. 102).
3. The notion of transferring equal amounts of suffering from one to another is impossible.
Nay, I go further, and I say that this whole idea of transferring certain exact and mathematically equal amounts of moral suffering from one person to another as if they were so many weights in a scale or so many chemical quantities in a laboratory, seems to me unthinkable: I cannot even imagine it. Persons are not things; personal feelings, states, conditions cannot be made to change places as if they were material substances. He who takes my place in suffering does not, and cannot, take my sufferings. These cannot be the same for him as they would be for me, simply because he is not I. In his place I should not feel precisely as he did; I might feel more, I might feel less; I should certainly feel differently; my penalty, therefore, cannot be transferred to him... (pp. 103-04).
And I further object to this doctrine of satisfaction of justice by exact equivalence of suffering because I see to what rash speculation, to what hideous conclusions, it has led. To rash and daring speculation, for instance, as to the nature and the intensity of the sufferings of Christ; to peeping and prying beneath the shadows of Gethsemane; to measuring of the exact tale of His agony and bloody sweat; to putting of His tears into our bottle and examining them by some quantitative analysis of our own; to showing how His six hours of suffering must, because He was infinite, have equalled the eternity of suffering due to all the sins of the finite human race; as if, on the supposition of the infinite overweighing the finite, an instant of suffering might not have sufficed as well as a century of it; and, worse than this--to the horrible conclusions that inasmuch as His sufferings were exact equivalents for demanded penalties, it would follow that any sins not forgiven could not have been atoned for; and therefore, that we must believe that He died only for the elect, and therefore that He who sent Him to die for men loved only the elect and hated all others, thus landing us in all the horrors of particular redemption and predestined reprobation (pp. 105-06).