Why Peter Failed

St. John Chrysostom

A third time the girl repeated: “You too were with that man yesterday,” but a third time he denied it. Finally Jesus looked at him, reminding him of his previous assertion. Peter understood, repented, and began to weep. Mercifully, however, Jesus forgave him, because he knew that Peter, being a man, was subject to human frailty. 

Now, as I said before, the reason God’s plan permitted Peter to sin was because he was to be entrusted with the whole people of God, and sinlessness added to Peter’s severity might have made him unforgiving toward his brothers and sisters. He fell into sin so that, remembering his own fault in the Lord’s forgiveness, he also might forgive others out of love for them. This was God’s providential dispensation. He to whom the Church was to be entrusted, he, the pillar of the churches, the harbor of faith, was allowed to sin; Peter, the teacher of the world, was permitted to sin, so that having been forgiven himself, he would be merciful to others.