III. Christ was in no sense the Author of His murderer's guilt
In fact, the case of the Crucified is so different from that of His crucifiers that what Christ undertook could not be reversed, while what they did could be wiped out. For He Who came to save sinners did not refuse mercy even to His murderers, but changed the evil of the wicked into the goodness of the believing, that God's grace might be the more wonderful, being mercifully put in force, not according to men's merits, but according to the multitude of the riches of God's wisdom and knowledge, seeing that they also who had shed the Saviour's blood were received into the baptismal flood.
For, as says the Scripture, which contains the Apostles' acts when the preaching of the blessed Apostle Peter pierced the hearts of the Jews, and they acknowledged the iniquity of their crime, saying, “what shall we do, brethren?” the same Apostle said, “Repent and be baptized, each one of you, in the name of Jesus Christ for the remission of your sins, and you shall receive the gift of the Holy Ghost. For to you is the promise, and to your sons, and to all that are afar off, whomsoever our Lord God has called,” and soon after the Scripture goes on to say: “they therefore that received his word were baptized, and there were added on that day about 3,000 souls.”
And so, in being willing to suffer their furious rage, the Lord Jesus Christ was in no way the Author of their crimes; nor did He force them to desire this, but permitted them to be able, and used the madness of the blinded people just as He did also the treachery of His betrayer, whom by kindly acts and words He vouchsafed to recall from the awful crime he had conceived, by taking him for a disciple, by promoting him to be an apostle, by warning him with signs, by admitting him to the revelation of holy mysteries, that one who had lacked no degree of kindness to correct him, might have no pretext for his crime at all.
Source: Sermons (New Advent)