3 Let us then not be ashamed of the Cross of our Saviour, but rather glory in it. For the word of the Cross is unto Jews a stumbling-block, and unto Gentiles foolishness, but to us salvation: and to them that are perishing it is foolishness, but unto us which are being saved it is the power of God. For it was not a mere man who died for us, as I said before, but the Son of God, God made man. Further; if the lamb under Moses drove the destroyer far away, did not much rather the Lamb of God, which takes away the sin of the world, deliver us from our sins?
The blood of a silly sheep gave salvation; and shall not the Blood of the Only-begotten much rather save? If any disbelieve the power of the Crucified, let him ask the devils; if any believe not words, let him believe what he sees. Many have been crucified throughout the world, but by none of these are the devils scared; but when they see even the Sign of the Cross of Christ, who was crucified for us, they shudder. For those men died for their own sins, but Christ for the sins of others; for He did no sin, neither was guile found in His mouth. It is not Peter who says this, for then we might suspect that he was partial to his Teacher; but it is Esaias who says it, who was not indeed present with Him in the flesh, but in the Spirit foresaw His coming in the flesh.
Yet why now bring the Prophet only as a witness? Take for a witness Pilate himself, who gave sentence upon Him, saying, I find no fault in this Man: and when he gave Him up, and had washed his hands, he said, I am innocent of the blood of this just person. There is yet another witness of the sinlessness of Jesus—the robber, the first man admitted into Paradise; who rebuked his fellow, and said, “We receive the due reward of our deeds; but this man has done nothing amiss; for we were present, both you and I, at His judgment.”
Source: Catechetical Lectures (New Advent)