Harnack didn’t much like Anselm’s Cur Deus Homo. Toward the end of his summary and critique in History of Dogma, vol. 6, he pays Anselm a back-handed compliment: “perhaps no one can frame a better, who isolates the death of Christ from His life, and wishes to see in this death something else than the consummation of the ‘service’ which He rendered throughout His life” (70).
For all his aversion to Anselm, his summary of the treatise is accurate, and especially helpful in laying out what Anselm did not intend to accomplish:
“It is (1) no doctrine of reconciliation in the sense of showing how the opposition of will between God and sinful humanity is removed; it is (2) no theory of penal suffering, for Christ does not suffer penalty; the point rather at which penalty is inflicted is never reached, for God declares Himself satisfied with Christ’s spontaneous acceptio mortis; just for this reason it is (3) no theory of vicarious representation in the strict sense of the term, for Christ does not suffer penalty in our stead, but rather provides a benefit, the value of which is not measured by the greatness of sin and sin’s penalty, but by the value of His life, and which God accepts, as it weighs more for Him than the loss which He has suffered through sin (between sin, therefore, and the value of the life of Christ there exists only an external relation; both are infinite, but the latter is more infinite; hence it more than satisfies God); it is, finally (4), not a theory which guarantees to the individual that he really becomes saved; it aims rather at only showing for all the possibility of their being saved; whether they shall be saved depends ‘on the measure in which men come to partake of so great grace, and on the degree in which they live under it,’ i.e., on how they fulfill the commandments of holy scripture” (63).
Harnack’s critique launches off from the last point, which he sees as the great flaw in Anselm: He cannot fulfill the “fundamental question of religion,” which is “personal certitude of salvation” (63). But the first points are worth contemplating, especially as Anselm is often seen as an advocate of penal substitution. For Anselm, though, satisfaction is not a fulfillment of the demand for punishment, but an alternative to punishment. Jesus restores God’s damaged honor, so that punishment is not needed – not for Jesus or for anyone else.