“Peter was now filled with repentance, as Judas in a few hours would be filled with remorse. Peter’s sorrow was caused by the thought of sin itself or the wounding of the Person of God. Repentance is not concerned with consequences; but remorse is inspired principally by fear of consequences; but remorse is inspired principally by fear of consequences. The same mercy extended to the one who denied Him would be extended to those who would nail Him to the Cross and to the penitent thief who would ask forgiveness. Peter really did not deny that Christ was the Son of God. He denied that he knew “the man,” or that he was one of His disciples. But he failed the Master. And yet, knowing all, the Son of God made Peter, who knew sin, and not John, the Rock upon which He built His Church that sinners and the weak might never despair.”
Venerable Fulton J. Sheen, Life of Christ, 493.