Of this Justification the causes are these:Trent immediately explains:
the final cause indeed is the glory of God and of Jesus Christ, and life everlasting;
while the efficient cause is a merciful God who washes and sanctifies gratuitously, signing, and anointing with the holy Spirit of promise, who is the pledge of our inheritance;
but the meritorious cause is His most beloved only-begotten, our Lord Jesus Christ, who, when we were enemies, for the exceeding charity wherewith he loved us, merited Justification for us by His most holy Passion on the wood of the cross, and made satisfaction for us unto God the Father;
the instrumental cause is the sacrament of baptism, which is the sacrament of faith, without which (faith) no man was ever justified;
lastly, the alone formal cause is the justice of God, not that whereby He Himself is just, but that whereby He maketh us just, that, to wit, with which we being endowed by Him, are renewed in the spirit of our mind, and we are not only reputed, but are truly called, and are, just, receiving justice within us, each one according to his own measure, which the Holy Ghost distributes to every one as He wills, and according to each one’s proper disposition and co-operation.
For, although no one can be just, but he to whom the merits of the Passion of our Lord Jesus Christ are communicated, yet is this done in the said justification of the impious, when by the merit of that same most holy Passion, the charity of God is poured forth, by the Holy Spirit, in the hearts of those that are justified, and is inherent therein: whence, man, through Jesus Christ, in whom he is ingrafted, receives, in the said justification, together with the remission of sins, all these (gifts) infused at once, faith, hope, and charity.Whether or not other aspects of Trent can be reconciled to Augustine, these conceptions are not consistent with Augustine. Augustine took the position that the thief on the cross had the faith that justifies without having baptism. To use Trent’s categories, the instrumental means for the thief was (in Augustine’s view) faith, not baptism.
Augustine connects the dots with Cornelius as well. Clearly he had the Spirit before baptism, which demonstrated his right standing with God (compare the argument about circumcision in Acts 15).
Augustine points out that the fact that the benefit can be invisibly applied (applied without the sacrament, the visible sign) should not lead us to scorn the sacrament. After all, even Cornelius was subsequently baptized.
And Cornelius said, "Four days ago I was fasting until this hour; and at the ninth hour I prayed in my house, and, behold, a man stood before me in bright clothing, and said, 'Cornelius, thy prayer is heard, and thine alms are had in remembrance in the sight of God. Send therefore to Joppa, and call hither Simon, whose surname is Peter; he is lodged in the house of one Simon a tanner by the sea side: who, when he cometh, shall speak unto thee.' Immediately therefore I sent to thee; and thou hast well done that thou art come. Now therefore are we all here present before God, to hear all things that are commanded thee of God."
Then Peter opened his mouth, and said, "Of a truth I perceive that God is no respecter of persons: but in every nation he that feareth him, and worketh righteousness, is accepted with him. The word which God sent unto the children of Israel, preaching peace by Jesus Christ: (he is Lord of all:) that word, I say, ye know, which was published throughout all Judaea, and began from Galilee, after the baptism which John preached; how God anointed Jesus of Nazareth with the Holy Ghost and with power: who went about doing good, and healing all that were oppressed of the devil; for God was with him. And we are witnesses of all things which he did both in the land of the Jews, and in Jerusalem; whom they slew and hanged on a tree: him God raised up the third day, and shewed him openly; not to all the people, but unto witnesses chosen before God, even to us, who did eat and drink with him after he rose from the dead. And he commanded us to preach unto the people, and to testify that it is he which was ordained of God to be the Judge of quick and dead. To him give all the prophets witness, that through his name whosoever believeth in him shall receive remission of sins."
While Peter yet spake these words, the Holy Ghost fell on all them which heard the word. And they of the circumcision which believed were astonished, as many as came with Peter, because that on the Gentiles also was poured out the gift of the Holy Ghost. For they heard them speak with tongues, and magnify God.
Then answered Peter, "Can any man forbid water, that these should not be baptized, which have received the Holy Ghost as well as we?"
And he commanded them to be baptized in the name of the Lord. Then prayed they him to tarry certain days.
Augustine goes on to say: “But what is the precise value of the sanctification of the sacrament (which that thief did not receive, not from any want of will on his part, but because it was unavoidably omitted) and what is the effect on a man of its material application, it is not easy to say.”
That’s perhaps the most troubling piece of all for those hoping to make Augustine in the image of Trent. Trent treats baptism itself as the instrumental means of justification, but it seems pretty clear that’s not what Augustine thinks.
And in case you think I’m speculating about his view on Cornelius, look at the parallel Augustine himself draws just shortly after:
And if any one seek for divine authority in this matter, though what is held by the whole Church, and that not as instituted by Councils, but as a matter of invariable custom, is rightly held to have been handed down by authority, still we can form a true conjecture of the value of the sacrament of baptism in the case of infants, from the parallel of circumcision, which was received by God’s earlier people, and before receiving which Abraham was justified, as Cornelius also was enriched with the gift of the Holy Spirit before he was baptized.Notice what Augustine concedes: he concedes that baptism and circumcision are parallel, that Abraham was justified before circumcision, and that Cornelius was analogously “enriched with the gift of the Holy Spirit” before baptism.
If Rome would concede the same, we would find faith alone as the instrumental means of justification, rather than baptism. Moreover, we would find reputed righteousness, rather than actual righteousness, the formal cause. Whether that latter point is something that Augustine himself held, perhaps we can consider another time.