Gospel (Mt 16,13-23) - At that time, Jesus, having arrived in the region of Caesarea Philippi, asked his disciples: "Who do people say that the Son of Man is?". They replied: "Some say John the Baptist, others Elijah, others Jeremiah or some of the prophets." He said to them: "But who do you say that I am?". Simon Peter replied: "You are the Christ, the Son of the living God." And Jesus said to him: «Blessed are you, Simon, son of Jonah, because flesh and blood has not revealed this to you, but my Father who is in heaven. And I say to you: you are Peter and on this rock I will build my Church and the powers of hell will not prevail over it. To you I will give the keys of the kingdom of heaven: whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven." He then ordered the disciples not to tell anyone that he was the Christ. From then on, Jesus began to explain to his disciples that he had to go to Jerusalem and suffer greatly at the hands of the elders, the chief priests and the scribes, and be killed and be resurrected on the third day. Peter took him aside and began to rebuke him, saying: «God forbid, Lord; this will never happen to you." But he, turning, said to Peter: «Get behind me, Satan! You are a scandal to me, because you do not think according to God, but according to men!

The commentary on the Gospel by Monsignor Vincenzo Paglia

Jesus questions his disciples about what people said about him. He knew well that the expectation of the Messiah was very keen, although he was understood as a strong man both politically and militarily. He was supposed to free the people of Israel from Roman slavery. In truth it was an expectation completely foreign to the mission of Jesus aimed, instead, at the liberation of men from the slavery of sin and evil. The rumors about Jesus were the most varied. But Jesus, after hearing these answers, goes straight to the hearts of the disciples: "But who do you say that I am?". Jesus needs his disciples to be in tune with him, to have a "common feeling" with him, to know his true identity. Peter takes the floor and, answering for everyone, confesses faith in him as the Messiah. And he immediately receives bliss. Peter, and with him that modest group of disciples, is part of those "little ones" to whom the Father reveals the things hidden since the foundation of the world. And Simon, a man like everyone else, made of "flesh and blood", in the encounter with Jesus receives a new vocation, a new task, a new commitment: to be a stone, that is, support for others, with the power to form new friendships and to dissolve the many bonds of slavery that prevent us from following the Gospel. Peter's response, made on behalf of everyone, comforts Jesus who opens his heart to them and shows what the end awaits him in Jerusalem will be: the Messiah is not a powerful man, but a weak one who will be killed. Peter doesn't understand what Jesus is saying; he thinks, in fact, that he is raving. And, driven by his instinct, certainly not by the faith that first made him speak, he wants to distance Jesus from his mission and from the road to Jerusalem. In truth, it is he who still has a long way to go on the path of understanding the Lord, like each of us. And Jesus says to him: «Get behind me, Satan!», as if to tell him to get back to following the Gospel.