Now, did Ambrosiaster use the phrase, Sola Fide? Sure. Did he mean by the phrase, Sola Fide, what Martin Luther and these Protestants mean by Sola Fide? I would argue in the negative.
I think the best place to show this would be to examine the verse in Scripture that Luther based his whole doctrine around—Romans 3:28:
“For we hold that a man is justified by faith apart
from the works of law.”
Luther took this verse and argued that what Paul is saying here is that man is justified (saved) by Faith alone and not at all by any kind of works (including good works, which includes upholding the Moral Law, i.e. the Ten Commandments, and upholding Christ’s commandments in the Sermon on the Mount. More will be said on this later). I would argue that Ambrosiaster understands Paul correctly and Luther does not.
Ambrosiaster was a master of the Old Testament and the Jewish Laws. He had a keen insight on how the New Testament fulfills the Old, which enabled him to be an exegete of Paul that rivals the likes of Chrysostom, Augustine, and the Tyconius the Donatist. So if we want to understand how Ambrosiaster interprets Paul, we must look at the context of what Paul is saying here in and around Romans 3:28.
The context of Romans 3:28 clearly shows that Paul does not mean that we are saved by “Faith Alone” (Sola Fide). In fact, Paul never uses the word “alone” in relation to Faith (pistis in the Greek). What Paul says is that a man is justified by faith APART from the works of the law (ergon nomou in Greek). This verse comes within the context of Paul arguing that God does not make distinctions between Jews and Gentiles (Rm 3:22) when it comes to being saved. Paul is countering the notion of the Jewish Christians who thought that a person had to first enter into the Mosaic covenant (through circumcision, which compelled the circumcised to adhere to the whole of the Jewish cultic—both ritual and purity—laws) before becoming a Christian and thus achieving salvation. If this were the case, then Gentiles who did not get circumcised would be excluded from the means of salvation. The very next verse (29) shows us this: “Or is God the God of the Jews only? Is he not the God of the Gentiles also? Yes, of Gentiles also…”
So what are these ergon nomou apart from which we are saved by faith? They are the Jewish cultic practices of circumcision, observing the Jewish Feasts and the new moon, ritual purity requirements, etc. To follow these would to be to become a Jew and no longer a Gentile. But God is the God of both the Jews AND the Gentiles and both the Jews and the Gentiles are saved by Christ! This is why in the next chapter (4), Paul shows that not all who are fleshly descendants of Abraham (those who are fleshly-circumcised Jews) are true descendants of Abraham (those who are circumcised in the heart). It is baptism into Christ that makes one a true heir, not circumcision of the flesh!
Paul is in no way arguing for Sola Fide here or anywhere else. He is saying that it is Faith (the kind of the Faith that includes the doing of good works and the keeping of the moral law) which saves, not the Jewish cultic laws.
So…what about Ambrosiaster? When he read this verse, did he make the same argument as Martin Luther, that one is saved by Faith Alone? Nowhere even close!
Gentilem dicit hominem pro certo haberi, quod justificetur credens nulla faciens opera legis, id est, sine circumcisione aut neomeniis, aut veneratione Sabbati.
He says the Gentile man, to be thought for sure, is justified believing, not doing any works of the law, that is, without circumcision or new moons, or veneration of the Sabbath.
As I said above, Ambrosiaster does use the phrase, Sola Fide, but the one place that—if he was in fact a proto-Lutheran—you would expect him to, he doesn’t. Instead he explicitly links the ergon nomou (opera legis in Latin) with circumcision, new moons, and observance of the Jewish Sabbath! So does Ambrosiaster teach the Protestant doctrine of Sola Fide? Absolutely not. Does he believe, as the Roman Catholic Church has held for two thousand years, that we are saved by Grace through Faith and good works (cf. Gal. 5: 6)? Yes, indeed. Listen to what he says in his commentary on St. Paul’s letter to Titus (chapter 3):
God in his mercy has saved us through Christ, by whose grace we have been born again and now receive the Holy Spirit in abundance, so that we may excel in good works. He will help us in everything, so that by these things we may inherit the kingdom of heaven. For this reason we must follow him with all devotion and obey his commands, because if there is anything beautiful in us, he has painted it with spiritual brushstrokes. (Italics added)
He is saying that the Holy Spirit helps us in everything, which includes the good works mentioned previously! And what is the result of these good works? “So that by these things we may inherit the kingdom of heaven.” Did you hear that? By good works we will inherit the kingdom of heaven, in other words, be saved. The good works we do after the grace of baptism are meritorious for salvation. I referred to Galatians 5:6 above. What does Ambrosiaster say about that verse?
What Paul is saying is clear; the hope of justification is in faith by the Spirit and not through the works of the law. By faith we serve God spiritually, by the devotion of our minds and the purity of our hearts. This is why the Lord said to the Samaritan woman: God is Spirit, and those who worship him must worship in spirit and in truth (italics in original). For this reason, neither uncircumcision nor circumcision is of any value, but faith in love (italics added) is required for justification. Faith must be accompanied by brotherly love if the believer is to be perfect (italics added). Finally, the Savior answered the scribe who asked him what the most important commandment was, as follows: You shall love the Lord your God with all your heart and with all your soul and your neighbor as yourself. On these two commandments hangs the whole law and the prophets (italics in original). Everything else is excluded (i.e. works of the law) and imperfect, because perfection is contained in these commandments.
Faith must be accompanied by brotherly love, i.e. good works. Hardly sounds like a proto-Lutheran to me! That’s probably because he was a Roman Catholic.
Ambrosiaster understands what Paul is teaching. So where did Luther go wrong? Well, for starters, his belief that Paul was teaching Sola Fide led him to believe that Paul contradicted the Epistle of James. James 2:24 states: “You see that a man is justified by works and not by faith alone.” Luther could not reconcile this verse of James with Romans 3:28, so he sought to have it removed from his German Bible, that is until he started losing followers and was urged to put it back in. Protestants nowadays will seek to reconcile the two verses by saying that Paul and James are speaking about different types of faith. But that is not right at all. Rather, they are speaking about different types of works. What Paul means by works we already showed above, namely circumcision and other Jewish cultic practices. What James means by works is good works—following the Moral Law of the Ten Commandments and the commandments of Christ. Luther completely missed this! You see, in his doctrine of Sola Fide, he excluded as works both the Jewish cultic laws and the Moral Law. The problem is that Paul did not mean to exclude the Moral Law. Neither did Jesus! We can see this in the Sermon on the Mount. Christ begins his statements with, “You have heard that it was said” X. Then, he doesn’t continue by saying that you don’t have to do that anymore. Rather, he says that you must uphold not only the letter, but go beyond it to the spirit (Cf. Mt 5). Also, in John 14:15 Christ says, “All you need is Faith Alone to be saved.” No? That’s not what he says? What he really says is “If you love me, you will keep my commandments.” Keeping the commandments of Christ is doing good works. But it is not good works that we do alone, but rather Christ working in us.
So you see, Ambrosiaster is not teaching the Lutheran doctrine of Sola Fide. Nor for that matter is any of the other Church Fathers, as my friend Taylor Marshall pointed out a while back.