The last pre-Reformation Church to be examined is also the most important one. Augustine (354-430) was the Bishop of Hippo and he is a giant among giants in Church History. It is well attested that his writings have had a massive effect on Church thought, stretching from medieval theology to the Reformation and even today. It is only appropriate that we should look into his highly influential views on Justification because they serve as a foundation for many coming after him.
Like many of the previous mentioned theologians, Augustine never explicitly taught on Justification but there is plenty of his work to glean from. In his writing, he shares many similarities with Athanasius in that justification for him is primarily about ontology. We will notice this in two of his major works dealing with this topic, On the Spirit and the Letter and On Faith and Works
On the Spirit and the Letter is an argument against the Pelagians who believe that man inherently has the ability to serve God in and of himself. Augustine attacks these Pelagians using the seemingly Protestant argument of Law and Gospel. Concerning the law, he writes that it shows the “foulness of their disease,” and that it “increased sinfulness rather than lessened it when the law entered in so that sin might abound.” When the law reveals how sick a person is, it leads him to the only doctor with the power to heal, namely Jesus. He writes concerning the Gospel, “He extends His mercy, not because they know him, but in order that they may know him, and he extends his righteousness, by which he justifies the sinner, not because they are upright of heart, but in order that they may be upright in heart.”  He also uses Romans 2 as evidence against Pelagianism when he compares it to Old Covenant Judaism. He remarks on how Paul used the law to show that the Jews were breakers of the law because they relied on their flesh and not on the Spirit of Christ.
Although Augustine sounds like a Protestant when he uses the Law and Gospel distinction to battle Pelagianism, he means something entirely different. Where Protestants harm with the law and heal with the Christ’s death, through the imputation of His righteousness, Augustine on the other hand, harms with the law and heals with Christ’s resurrection, there by imparting His righteous Spirit. For Augustine, Christ’s death gave us a clean record but Christ’s life gave us His righteousness so that we can be justifiably righteous before God. Not on our own strength but on the strength that He gives us. Romans 5.5 is a key verse for him in that we are made right with God by Him pouring His love into our hearts through the Holy Spirit; justification for Augustine is primarily transformational. We become righteous receiving the Spirit of Christ by faith.
So what exactly is the justifying role of the cross for Augustine? According to him it has a dual purpose. In On Faith and Works, Augustine is arguing against Anti-Nomians. To refute them, he writes about how on the cross, Jesus crucified the record of Christians’ sins; yet, that is not the only aspect of it. He also says through union with Christ believers were crucified to the world so that they would die to sin. Faith achieves two things simultaneously for him. For Augustine, the cross makes one righteous both forensically and intrinsically. 
Augustine is similar to Athanasius in many ways; In fact, Augustine was probably influenced by Athanasius. In their understanding of justification , the atonement made Christians innocent before God, but it was Love of God poured into our hearts that God that made them righteous; both of these were essential. For Augustine, his understanding of justification was developed by his conflict with the Pelagians. It only makes sense that he would combat them by displaying the depravity of humanity and hearkening the Grace of God which gives a new nature through the Spirit. It is the new man, who produces the fruit of good works, that God declares to be righteous.
 Alister McGrath, 24.
 When I mention ontological changes this is what the Reformed tradition would associate with Sanctification.
 Augustine, On the Spirit and the Law, 9.
 Ibid. 11.
 Ibid. 13.
 In comparing the Law of Works vs. Law of Faith Augustine states in paragraph 22: By the law of works God says: Do what I command! By the law of faith we say to God: “Give what you command! After all, the law commands in order to remind us of what faith should do.”
 Augustine, On Faith and Works, 15.