1. It is highly immoral.
First, a theory of penal substitution strikes many of us today as highly immoral since it claims that God punishes the innocent for the transgressions of the guilty. The only way to make some moral sense of this is to interpret it in terms of a feudal concept of honour. God is then viewed as a feudal lord whose honour has been violated by our disobedience. His honour now requires satisfaction, and it does not matter who provides that satisfaction. Thus Christ in his perfect humanity is able to make the adequate satisfaction that is beyond our means to provide. Such feudal honour might have been familiar in the twelfth century, but for most of us today it goes against the grain to look on God as a feudal Lord demanding this kind of honour (p. 75).
It seems that all of the various theories of the atonement were formulated against the backdrop of the particular culture and times in which the initial proponent of the theory lived. The theory made sense to the people living in that culture but make no sense to people living in a different culture.
2. It devalues the person.
...people participate in agreements of rights and obligations for the sake of the advantage that each party can gain for him or herself. Under such an agreement I do not value you for who you are but for the services that you are to provide for me, and you too value me merely as a provider of services under the agreement. As such you are not irreplaceable for me, nor am I for you. Anybody else who could provide the same services, would do just as well. If this is the sort of relationship we have with God, it means that we do not love God for himself alone, but merely as a provider of eternal happiness. To put it crudely: we value heaven more than we value God! On the other hand, God does not love me for myself alone, but merely for the obedience with which I render him honour. To put it crudely: God values my serving his honour more than he values me. For this reason, too, I am replaceable for God by anybody else who is able to satisfy his honour adequately. It does not matter to him whether it is I or Christ in my stead who does so, provided his honour is satisfied. If, as I have argued, the ultimate value of my very existence is bestowed on me by the fact that God loves me and not merely my services apart from me, then it is clear that this view entails a concept of God that is radically defective from a religious point of view (pp. 75-76).
3. It sets up a false dichotomy.
Thirdly, this view on the divine-human relationship cannot account adequately for the nature of divine forgiveness. . . . in an agreement of rights and duties the only alternative for satisfaction or punishment is condonation. In this context, therefore, divine forgiveness can only be viewed as a form of condonation that fails to take sin seriously. In the words of Gustaf Aulen, . . . either a forgiveness of sins by God, which would mean that sin is not treated seriously and so would amount to a toleration of laxity, or satisfaction. No other possibility is regarded as conceivable [Christus Victor, pp. 145-46](p. 76).
So, the PST sets up a false dichotomy--either God condones sin (if he forgives without punishment) or God punishes sin. Brummer maintains that there is a third option between condonation and satisfaction. Forgiveness is that third option and it does not represent condonation as the PST implies.
Herein lies the difference between forgiveness and condonation. If you were to condone my action, you would deny that it an action that caused you real injury, and thus also deny that there is anything to forgive. If, on the other hand, you forgive me for what I have done, you claim that my action did cause you injury, but you would rather bear the injury than abandon the fellowship that I have damaged by my action. Forgiveness entails that, for the sake of reconciliation, you give up your right to pay me back in my own coin by demanding satisfaction or by punishing me: "The power to forgive is not to be obtained for nothing, it must be bought at a price, it must be paid for with the suffering of him who has been sinned against" [O. C. Quick, Essays in Orthodoxy, 1916, pp. 92-93]. One of the fundamental characteristics of forgiveness is therefore that "the one who forgives is the one who suffers" [J. Edwin Orr, Full Surrender, 1951, p. 22]. Thus forgiveness costs you something, whereas condonation is a denial that there are any serious costs involved (p. 41).
4. It destroys the unity of the Trinity.
Fourthly, the account that this theory of atonement provides of the work of Christ can hardly be said to do justice to the unity between the Persons of the Trinity. . . . the unity of the Father and the Son involves an identity of will and essence. This entails that their purpose and attitude toward us should be similarly identical: the purpose and attitude of the Son should be a direct expression of that of the Father. The doctrine of penal substitution presents a very different view of the relationship between the Father and the Son. In the words of David Smith:
"The theory stands in direct and open contradiction to the fundamental article of the Christian faith, that Christ is one with God--one in character and purpose and disposition toward the children of men. It places a gulf between God and Christ, representing God as the stern Judge who insisted on the execution of justice, and Christ as the pitiful Saviour who interposes and satisfies his legal demand and appeases his righteous wrath. They are not one either in their attitudes towards sinners or in the part which they play. God is propitiated, Christ propitiates; God inflicts the punishment, Christ suffers it; God exacts the debt, Christ pays it. This is the fundamental postulate of the theory, God and Christ are not one in character or purpose of disposition toward sinners" [The Atonement in the Light of History and the Modern Spirit, 1918, p. 106].This does not deny that the Father agrees with the Son adopting the "character or purpose or disposition toward sinners" that he does. However, "agreeing" does not amount to "sharing." In terms of Bernard's distinction [Bernard of Clairvaux, Serious Song of Songs, sermon 71], "there must be at least two wills for there to be agreement." Agreement between the Father and the Son would account for no more than a "union of wills" and not for the "unity of will" which constitutes the unity between the Father and the Son (pp. 76-77).
5. It makes the atonement something done to God rather than by God.
Fifthly, this view contradicts the patristic intuition that atonement is something done by God not to God. Thus Aulen argues that on this view God is no longer the direct agent of atonement. It is Christ in his humanity who makes satisfaction to God. "The satisfaction must be made by man; and this is precisely what is done in Christ's atoning work . . . [Christus Victor, p. 103]. It is on this point that Aulen rejects Anselm's "Latin theory" of atonement in favour of what he calls the "Classical theory" of Irenaeus who "does not think of the atonement as an offering made to God by Christ from man's side, or as it were from below; for God remains throughout the effective agent in the work of redemption" [Ibid., p. 50]. It is true that Anselm and his followers claimed that God "gives" or "sends" Christ to act as Mediator. In this sense God is the initiator or author of the Atonement but he is not the agent who carries it out. The agent of the Atonement is Christ in his humanity (p. 77).
6. It does not necessarily produce reconciliation.
Finally, penal substitution satisfied the demands of retributive justice. . . . retributive justice merely removes guilt but it does not restore fellowship. Sin is seen here as guilt rather than as estrangement. Salvation through penal substitution is therefore the removal of guilt rather than reconciliation with God that overcomes estrangement. In this sense the theory is not a theory of atonement (in the sense of "at-one-ment") at all. If we look on sin as estrangement from God, we will need a theory of atonement that explains how we can be reconciled with the God from whom we have become estranged (p. 77).
So, here is another theologian showing that the PST is internally contradictory to Christian theology.