III. The Devil's devices were turned against himself
And in order that He might set the human race free from the bonds of deadly transgression, He hid the power of His majesty from the raging devil, and opposed him with our frail and humble nature. For if the cruel and proud foe could have known the counsel of God's mercy, he would have aimed at soothing the Jews' minds into gentleness rather than at firing them with unrighteous hatred, lest he should lose the thraldom of all his captives in assailing the liberty of One Who owed him nought.
Thus he was foiled by his malice: he inflicted a punishment on the Son of God, which was turned to the healing of all the sons of men. He shed righteous Blood, which became the ransom and the drink for the world's atonement. The Lord undertook that which He chose according to the purpose of His own will. He permitted madmen to lay their wicked hands upon Him: hands which, in ministering to their own doom, were of service to the Redeemer's work. And yet so great was His loving compassion for even His murderers, that He prayed to the Father on the cross, and begged not for His own vengeance but for their forgiveness, saying, “Father, forgive them, for they know not what they do.”
And such was the power of that prayer, that the hearts of many of those who had said, “His blood be on us and on our sons,” were turned to penitence by the Apostle Peter's preaching, and on one day there were baptized about 3,000 Jews: and they all were “of one heart and of one soul,” being ready now to die for Him, Whose crucifixion they had demanded.
Source: Sermons (New Advent)