But he turned, and said unto Peter,
Get you behind me, Satan: you are an offense unto me: for you consider not the things that be of God, but those that be of men.
All Commentaries on Matthew 16:23 Go To Matthew 16
Therefore, the rest being troubled and in perplexity, Peter again in his ardor alone ventures to discuss these things. And he does not discuss them openly but only when he had taken him aside. Having separated himself from the rest of the disciples, he says, “God forbid, Lord! This shall never happen to you.” What is happening here? The very one who had obtained a revelation, who had been blessed, has now so soon fallen away, so as now to fear the Passion of the Lord, and thereby his faith has been overthrown. It is remarkable that Peter, who had not yet been fully instructed in the course of revelation, should come up with these responses. The larger picture had not yet been revealed to Peter, and he was confused and overwhelmed. Peter had learned that Christ is the Son of God. But he had not learned of the mystery of the cross and the resurrection. It was as yet not manifested to him. It remained hidden. Do you see how correct Jesus was in forbidding them not to declare his identity publicly? For if it so confounded the disciples, who were being made aware of it, who knows what the response of others might have been. This is why he rebuked Peter and called him Satan: to signify that he is coming to his future suffering voluntarily. The Gospel of Matthew, Homily