In my reading of St. Gregory the Great’s Moralia in Iob I recently came across a passage that is famous for (supposedly) anticipating the Reformation era penal substitution theory of atonement:
It is to be explained, however, how God can be just, how he disposes all things wisely, if he condemns the one who does not deserve punishment. Our Redeemer surely should not be punished on his own account, because he did not do anything to bring guilt upon himself. But if he did not accept a death he did not deserve, he would never free us from the death we deserve. The Father is just; he punishes the just one. All his arrangements are just; therefore, he justifies every thing because he condemns the sinless one for the sake of sinners. All the chosen will rise to reach the summit of justice, because he who is above all things accepted the condemnation wrought by our injustice. (3.XIV.27)
He begins with a question that was to dominate later debate “how God can be just… if he condemns the one who does not deserve punishment.” But it is notable that his answer does not give an account of how atonement functions, but simply appeals to the general meaning of divine just: that He makes us just. As it stands Gregory’s reflection could be reconciled with any number of theories of atonement.