PS from the Apostles to Milan
313AD marks an important date in the history of Christianity, when the Emperor Constantine announced that Christianity was no long illegal within the Roman Empire. Christianity went through a huge number of changes in the fourth century as a result. It moved quickly to become the religion of the Empire, with the Emperor as its head. The power of the state was used to suppress those deemed heretics. The world was quickly filled with nominal Christians who were "Christians" because it was the state religion, not out of any conviction they had. There were councils, creeds, and controversies which often got as political as they did religious. Thus, for those of us studying the theology of the early church, the date 313AD marks a distinct boundary.
The period from the time of the apostles and the New Testament to the Edict of Milan in 313 AD spans about 200 years. During this time, many books and letters were written by Christians and quite a large number of them survive. To give you some idea of how many, the standard English translation of these writings which contains most of the surviving works by most of the orthodox Christian writers of this period runs to over 6,500 pages. By comparison the average bible runs to about 1,000 pages. There is a lot of writings that survive from this early period, of all types: Pastoral letters, defenses of Christianity, commentaries on biblical books, descriptions of church practices, critiques of heretics, explanations of Christian doctrine, essays in defense of specific doctrines etc, and so we are far from ignorant about the theology of this period.
In the recent work written in defense of the doctrine of Penal Substitution Pierced For Our Transgressions, the authors attempt to respond to the standard claim that Penal Substitution was not taught prior to about 1500AD. I have studied the historical development of church doctrine, and I would myself from my own studies agree with that standard claim. Nothing that the writers of the book PFOT say convinced me otherwise. In order to "disprove" this standard claim which they believe is incorrect, the authors of PFOT say they will give a comprehensive list of quotes from the Church Fathers which teach penal substitution. This demonstrates, according to them, that PS has been taught consistently as an important doctrine throughout Church history.
Now the first thing I looked for when I saw their list was what references they make to writers from before 313AD, since writers from that period are one of my particular hobbies. So in their comprehensive list, how much of the 6,500+ pages surviving from 100AD to 313AD do they find teaches penal substitution? The answer is one paragraph... one paragraph buried deeply in the work of one writer in over six thousand pages of writings by more than twenty writers spanning two hundred years. Yeah, that shows it's a "central" doctrine... not. The central doctrines from this period are obvious - funnily enough they get talked about, and twenty pages per main doctrine would not be sufficient to hold all the quotes from these writers on major subjects of their theology which get mentioned by nearly every writer (depending on the topics of their works). Certainly if someone was going to allege to me that something was a standard doctrine in this period, I would want to see clear quotes from at least three authors that were well-spaced chronologically and geographically.
But anyway, this one paragraph, is in Justin Martyr's Dialogue with Trypho, section 95 out of 142. Justin's Jewish critic Trypho has just brought up the Old Testament passage about how those who are crucified are cursed by God, and therefore Jesus could not be the Messiah. Justin replies that he does not believe God cursed Jesus but rather suggests that this passage be linked with the "cursed is everyone who doesn't do all the things stated in the law" passage to mean that the curse Jesus experienced was not the curse of a God who rejected him, but that a curse against us was transferred to him. Is this teaching penal substitution? Well of course that depends on how you want to define penal substitution. The punishment Justin depicts Christ saving us from here is this-worldly - a curse pronounced by the law. The ancients believed in curses and dealt with them on a regular basis via various transfer rituals. Justin's not talking about us going to hell or heaven, it's just a regular curse and Christ transfers it. The effects of Christ's act is thus universally applicable, the curse is removed from everyone, no faith or anything like that is needed.
So Christ takes this curse from us to himself, and the curse is indirectly from God and applicable because of human sin. But there the similarity with PS ends... Christ's doing this is universally applicable and there is no faith needed on our part, and we do not gain eternal life because of it. It's not because God was forced to punish human sin, or because he was wrathful against us. It thus has similarities with Penal Substitution, but it's not PS. How widespread or important was this view among these early writers? Well, no other writer mentions it. Justin's key sentence in the passage concerned is phrased hypothetically as a question. Justin himself in the very next section says that for him the most worthwhile interpretation of the passage which Trypho has brought up (which says that those who are crucified are cursed) is not that Jesus was cursed by God but as a prophecy of the Jews crucifying and cursing both Christ and the Christians (Dial. 96).
In Justin's view, as clearly explained elsewhere in his writings repeatedly (not in one paragraph), salvation operates the same way it does in all the other writers of this period - a virtuous life and character comes through following the teachings of Jesus and leads to a positive final judgment. The idea that Justin teaches Penal Substitutionary atonement as his central view of salvation is simply flat-out not true. Hence the idea implied by PFOT that this one paragraph from Justin shows that PS was generally taught in this period is laughable. They can only find one paragraph in a corpus of well over 6,500 pages of the earliest Christian writings and that paragraph doesn't even teach their doctrines.