The author of this piece is wrong I believe
Mt 16:13 When Jesus came into the coasts of Caesarea Philippi, he asked his disciples, saying, Whom do men say that I the Son of man am?
Mt 16:14 And they said, Some [say that thou art] John the Baptist: some, Elias; and others, Jeremias, or one of the prophets.
Mt 16:15 He saith unto them, But whom say ye that I am?
Mt 16:16 And Simon Peter answered and said, Thou art the Christ, the Son of the living God.
Mt 16:17 And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed [it] unto thee, but my Father which is in heaven.
Mt 16:18 And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it.
Mt 16:19 And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven.
Mt 16:20 Then charged he his disciples that they should tell no man that he was Jesus the Christ.
Mt 16:21 From that time forth began Jesus to shew unto his disciples, how that he must go unto Jerusalem, and suffer many things of the elders and chief priests and scribes, and be killed, and be raised again the third day.
Mt 16:22 Then Peter took him, and began to rebuke him, saying, Be it far from thee, Lord: this shall not be unto thee.
Mt 16:23 But he turned, and said unto Peter, Get thee behind me, Satan: thou art an offence unto me: for thou savourest not the things that be of God, but those that be of men.
The very start of this conversation concerned, “Whom do men say that I the Son of man am?”
the correct answer, given by Peter, was THE ROCK Jesus spoke of:” Thou art the Christ, the Son of the living God.”
That is the key to it all. What other foundation would the Son of God build upon, a man who Jesus called SATAN in the following verses?
That Jesus is the Christ is enough. The Messiah, the Lamb of God, the Saviour of the world.
THAT is the ROCK which Jesus spoke of.
To say a MAN IN THE FLESH is that rock is blasphemy.
“To say a MAN IN THE FLESH is that rock is blasphemy.”