Chafer was a strong believer in the Penal Substitutionary Theory (PST) of the Atonement. In volume 3 of his Systematic Theology, he writes:
As the term vicar refers to a deputy or agent who acts in the place of another, thus the word vicarious means that one takes the place of another, serving or acting as a substitute. In the case of an obligation between man and man, the law permits the debt to be discharged by a third party, provided no injustice to others is wrought. However, the divine permission for a substitute to act for man in his relation to God is one of the most fundamental provisions of saving grace. As fallen man stands obligated to God as an offender--both in his federal head and in himself--against his Creator and against the divine government, he owes an obligation which he could never pay in time or eternity. Unless a vicar shall intervene there is no hope for any member of this fallen race. No sin-laden human being could be vicar for a fellow being. The vicar must be sinless as well as prepared to bear those immeasurable judgments which divine holiness must ever impose upon sin. (p. 58)Chafer maintains, as Anselm did nearly 1000 years prior to him in Cur Deus Homo?, that God had to become man in order to redeem man.
The difficulty in accounting for the sufferings and death of Christ is greatly increased when it is considered that He was Himself the holy, undefiled and spotless Lamb of God. In this there is no receding from the essential truth that Christ became a legal substitute (emphasis mine), which undertaking demanded of Him that He meet the judgment due for the failure of those whom He represented. He became the voluntary Bondsman, their Surety (Heb. 7:22), meeting their liabilities and providing the required ransom. This is the precise import of the language employed in the Sacred Text. If it be inquired to whom the ransom was paid and whose demands are met by the payment, it is answered that the obligation is to God in respect to His holiness . There is a distinction between pecuniary and moral obligations; yet the Bible implies that an actual parallel exists between these when it speaks of the sacrifice and blood of Christ as a ransom and a redemption. A debt of obligation to a broken law or offended authority may be as real as a financial debt which is contracted with a fellow being. A criminal in prison, or when executed, is paying the debt he owes to outraged law and government. The basis of all obligation is the duty of the creature to fulfill the purpose and will of the Creator. In this, all have sinned and come short of the glory of God. A sinless Substitute purchased the deliverance of sinners (Act 20:28), He paid the required price (1 Cor. 7:23), a ransom (Matt. 20:28), and redemption (Eph. 1:7). The legal aspect of this revelation is that God required the sinner's obligation to be met. There could be no receding from this holy demand. The love of God is seen in the fact that Christ voluntarily consented to pay the debt, and in the fact that the Father accepts the payment at the hand of the Substitute. . . . . it is puerile to assert that the Bible does not teach the doctrine of substitution. God is "of purer eyes than to behold evil, and cannot look on iniquity" (Hab. 1:13). He rather magnifies the law and makes it honorable (Isa. 42:21), and no more perfect upholding of the law of His holy Being could be conceived than is exemplified in the voluntary assumption of a qualified substitute taking on himself the discharge of the sinner's obligation (2 Cor. 5:14, 19, 21) . . . (pp. 66-67).Chafer is right that the Scripture does often speak of sin as a debt and that the death of Jesus' satisfies that debt. However, as even he acknowledges, the debt is not to be taken in literal financial terms.
The import of these and other Scriptures is not that Christ, in a commercial sense, bore the sin of the world. This would mean that had there been one more sinner His sufferings would have been increased by so much, or had there been one less sinner His sufferings would have been decreased by so much. In a forensic sense Christ made a legal sacrifice for sin the value of which is available for all who believe. Had it pleased God to terminate human sin immediately after the first human sin, it would have required precisely the same sufferings and death on the part of the Savior to save that one sinner from his one sin (p. 67).So, the use of "ransom" or "purchase" in reference to what Jesus accomplished on the cross can only be understood metaphorically or analogically. It cannot, according to Chafer, be taken in a literal commerical sense. It is much like the saying: "The price of liberty is eternal vigilance." It is not a payment made to someone; its the action required in order to preserve freedom. The death of Jesus was the action required to save man but it was not a commercial transaction. This admission by Chafer undercuts the defense of the PST which says that the debt of man's sin was like a monetary debt that can be transferred. A substitute can legally pay the monetary debt owed by another, but a substitute cannot pay the criminal penalty owed by another. Chafer does not seem to be aware of this problem in his defense of the PST.
The only way that the death of Jesus could be legitimate legally would be if he were subjectively a sinner himself. In other words, if man's sin somehow became Jesus' sin. He quotes Daniel Williams, who offers this theory in Gospel Truth Stated and Vindicated (1692):
"This transaction of our sins to Christ is a real act; our sins so became Christ's that He stood the sinner in our stead . . . To speak more plainly: Hast thou been an idolater, hast thou been a blasphemer, hast though been a murderer, an adulterer, a thief, a liar, a drunkard? If thou hast part in the Lord, all these transgressions of thine become actually the transgressions of Christ" (emphasis mine, cited in Chafer, p. 70).But Chafer and virtually all evangelicals vehemently reject this notion. He writes:
Nothing is more absolutely true, nothing is more sacredly or assuredly believed by us, than that nothing which Christ did or suffered, nothing that He undertook or underwent, did, or could, constitute Him subjectively, inherently, and thereon personally, a sinner or guilty of any sin of His own. To bear the guilt or blame of other men's faults--to be "alienae culpae reus"--makes no man a sinner, unless he did unwisely or irregularly undertake it (p. 71).Chafer has here undercut another possible way to explain the justice of the PST and is essentially left with the appeal to mystery. He concludes:
There is no ground for surprise that an inscrutable mystery is confronted when the infinite God is accomplishing His greatest undertaking, and in a way which is consonant with things eternal and celestial (p. 72).Even though theologians have spilled a lot of ink on this subject, at the end of the day, they are left with no real answer. Thus, they appeal to mystery. My problem with this appeal, as stated before, is that it is not an answer at all. It is an admission of the problem but not a solution. In addition, if man is made in the image of God and has received his sense of morality from God, as evangelicals hold, then why can't we trust our intuition that punishing an innocent is wrong? If we can't trust our moral intuitions when it comes to punishing an innocent, which is virtually the unanimous opinion of mankind, then how do we know that we can trust any of our moral intuitions? Second, if God's ways are beyond our comprehension, how can we say anything definitively about God? It may be that what theologians think they know about God and his ways are incorrect due to the partial nature of the knowledge. If this is so, then one has just thrown out the whole enterprise of Christian theology.