“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? And they said, Some say that thou art John the Baptist: some, Elias; and others, Jeremias, or one of the prophets. He saith unto them, But whom say ye that I am? And Simon Peter answered and said, Thou art the Christ, the Son of the living God. 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. 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.” Matthew 16:13-18
The Greek word for Peter is the word petros, which is a piece of rock, whereas the Greek word for ROCK, is the word petra which describes a mass of rock. Keep in mind that the Lord questioned his disciples as to what the people were saying about him. Jesus wanted to know who they thought he was.
They told him that some thought that he was John the Baptist, which he was not. Some thought that he was the prophet Elijah, which he was not. Some thought that he was the prophet Jeremiah or some other prophet, which he was not.
Jesus then asked THEM who they thought he was, and Peter (Simon) responded and told him that he was the Christ (Messiah), the Son of the living God, which he WAS! The Lord Jesus Christ then told Peter that flesh and blood (another human being) did not reveal that information to him, but his Father which is in HEAVEN!
Jesus was letting Peter and his fellow disciples know that the church of God would be built upon the TESTIMONY, which Peter spoke, and the revelation which comes from above. The outside people did not have the revelation which Peter and his fellow disciples had, and thus they believed Jesus to be John the Baptist, Elijah, Jeremiah or one of the prophets.
The true believer in Jesus Christ who has been genuinely born again of the Spirit, KNOWS that Jesus was indeed the Christ (Messiah) and the Son of the living God! That truth cannot be understood by the natural man, but ONLY by the Spirit of the living God.
“Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God. Which things also we speak, not in the words which man’s wisdom teacheth, but which the Holy Ghost teacheth; comparing spiritual things with spiritual. But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned.” 1 Corinthians 2:12-14
Related Study: Was The Apostle Peter The First Pope?