I don't think I am. It's just a question of reading the plain meaning of the verses.
'Surely He has borne our griefs and carried our sorrows; yet we esteemed Him stricken, smitten by God and afflicted....' We can surely agree that on the cross our Lord was indeed
'stricken' and '
afflicted' - 'we' were right about that - but by whom? Verse 10 tells us:
'Yet it pleased the LORD to bruise (or
'crush')
Him; He has put Him to grief.' Now unless you are going to follow
@JonC and insist that what the verse means is that it did NOT please God to bruise the Lord Jesus and that He did NOT put Him to grief, then you are faced with the fact that it was God who struck Him. The 'but' is making the contrast that 'we' supposed that God struck Him for His own sins, when in fact,
'The LORD has laid on Him the iniquity of us all ........ For the transgressions of my people He was stricken ....... For He shall bear their iniquities.'
PSA is perfectly clear in the Scriptures. The ECFs did not tend to go into great detail concerning the atonement. They were more taken up with the Trinity and the Person of Christ. But where they did, they gave clear witness to Penal Substitution. I have given several examples of this over the last several years, and I suppose I can look them all out again if you insist. However, here are a couple of short ones from two of the earliest Fathers. First, Clement of Rome:
'In love the Ruler took us to Himself. Because of the love He had towards us, Jesus Christ our Lord gave His blood for us by the will of God, His flesh for our flesh; His life for our life.' [Clement of Rome:
Epistle to the Corinthians xlix]
Next, Irenaeus:
'He who was powerful Word and also truly man redeemed us by His own blood by a rational transaction, and gave Himself as a ransom for these who had been taken into captivity ......... The Lord redeemed us by His blood, and gave His life for our life, His flesh for our flesh, and poured out the Spirit of the Father to unite us and reconcile God and man.....'
These extracts are very brief, but they show that PSA existed, as it were,
in embyro even among the earliest writers. Of course it did, since it is so clearly exhibited in the Bible.
You do a great dishonour to the many Protestant martyrs of the 16th Century who gave their lives in defence of Protestant teaching. However, light did not come all at once in the Reformation. John Robinson, leader of the Pilgrim Fathers when they were in Holland said, in his farewell speech to those leaving for America in 1620, charged them to follow him no further than he followed Christ, saying that,
"It is not possible the Christian world should come so lately out of such thick Antichristian darkness [as that which pertained before the Reformation]
and that full perfection of knowledge should break forth at once.'
[More on Robinson's speech here:
John Robinson’s farewell to the Pilgrim fathers ]
It was the 17th Century Particular Baptists who, to my mind, went furthest in completing the Reformation. They brought to an end the last vestiges of Romanism: infant baptism and the state church, whilst holding firm to the
Five Solas of the Reformation: Grace alone, Christ alone, Faith alone, the Scriptures alone, to the glory of God alone. Yet there is a sense in which the Reformation is never finished. The Reformers held that
Ecclesia Reformata semper Reformanda; the Reformed church is always in need of reformation.