During the Reformation, the reformers favoured the doctrine of penal substitution to describe how Jesus’ death on the cross saves us. Penal substitution means that the Father punished (penal) the Son instead of us (substitution) for our sins.
Some people have found this doctrine offensive because it constitutes child abuse. As this reasoning goes, if a father punishes an innocent son by placing him a cross (a tortuous death), this would be child abuse. Likewise, God the Father would be committing child abuse by punishing the Son on the cross. Others may disagree with penal substitution because it sounds like a pagan idea rather than a Biblical idea. Still others might simply assert that penal substitution arises out of medieval worldview, where God is a wrathful god who punishes sins and a person must receive punishment to satisfy justice.
It is this latter accusation, which I would like to respond to. The doctrine of penal substitution is not a medieval idea. It is a Biblical idea and an early Christian doctrine. I will focus on this latter idea (penal substitution as an early Christian doctrine) here.
The Letter to Diognetus
The anonymous letter written to Diognetus dates back to sometime in the 100s or possibly the 200s. It could have been written within the living memory of some of the apostles. So it is early, and it is certainly not medieval. And in this letter, the author clearly affirms something like penal substitution and presents penal substitution as if it were non-controversial. Consider the following.
In chapter 9 of the letter, the author explains how Christ’s salvation is a mystery revealed. Before the mystery was revealed, however, humans learned that their deeds were wrong and that they could do nothing on their own to enter into the kingdom of heaven (9.1). The wages of unrighteous are “punishment and death,” writes the author (9.2).
But God revealed his goodness at the right time: “he took upon himself our sins; he gave his own son as a ransom for us—the holy for the lawless, the good for the evil, the righteous for the unrighteous, the incorruptible for the corruptible, the immortal for the mortal” (9.2). In essence, the Son died in our place.
After all, reasons the author, “… how can any other thing be able to cover our sin if not his righteous?” (9.3). Since we are lawless and ungodly, only the Son of God is able to justify us (9.4).
The reality of God’s justification overwhelmed the author who breaks into praise: “Oh, what sweet exchange! Oh, the inscrutable God! Oh, the unexpected blessing!” (9.5). He is so joyful because “the lawlessness of many was hidden in one righteous person, and the righteousness of one person justifies the many who are lawless” (9.5).
The author of the letter knew well that the wages of his sin is punishment and death (9.2). But through the “sweet exchange” (9.5) whereby the Son of God takes upon himself our sins as a ransom (9.2), we are saved.
Although the author does not spell it out precisely, he celebrates the fact that we no longer have to receive the punishment of sin because Christ took our place.
The idea that penal substitution is a medieval idea, which can be safely overlooked today, is a false one. The early church in various degrees taught a kind of penal substitution. I grant that it is not exactly the same version of penal substitution that Calvin, for example, taught. I also grant that we may need to reform our explanation of how Christ’s death saves us. We may need to sharpen our language and revisit the Bible. But we cannot reject penal substitution as a cultural artifact of the medieval mindset. At the end of the day, we must not rely on history to define our theology; we must turn back to the Bible to see how it portrays the death of Christ.