And I say also unto thee, That thou art Peter (πέτρος), and upon this rock (πέτρᾳ) I
will build my church; and the gates of hell shall not prevail against
it. (Matthew 16:18, KJV)
The word Peter signifies a stone--a rolling stone.
Peter was not the Rock upon which the church was founded. The gates of hell did prevail against him when he denied his Lord with cursing and swearing, as well as when the Tempter induced him to speak words of temptation toward Christ, prompting Jesus' words "get thee behind me, Satan" (see Matthew 16:23).
But Peter would witness for Christ. In the words of the great protestant reformer, Ulrich Zwingle: "Let not this accusation move you. The foundation of the church is the same Rock, the same Christ, that gave Peter his name because he confessed him faithfully. In every nation whoever believes with all his heart in the Lord Jesus is accepted of God. Here, truly, is the church, out of which no one can be saved." – D’Aubigne, London ed., b. 8, ch. 11.
Following his conversion (after his denial of Christ), Peter did confess Christ faithfully. And Zwingle saw this as the reason that Christ had named Peter a stone.
Remember these words?
And he answered and said unto them, I tell you that, if these should
hold their peace, the stones would immediately cry out. (Luke 19:40,
The word "stones" (λίθος) in this text is yet another synonym in Greek for the words petros and petra. Those who witness for Christ are as stones crying out.
The Greek shows that the word Jesus used to reference Peter was a different word than the one used for the rock upon which God was to build His church. Jesus was, therefore, making a clear distinction between the two words, placing them in contrast with each other. In effect, Jesus was saying that Peter was not the rock upon which the church was to be built.
The church was built upon One against whom the gates of hell could not prevail.
Ironically, despite Jesus' clear words and their implications, many have gotten it the other way around.
If Jesus had delegated any special authority to one of the disciples above the others, we should not find them so often contending as to who should be the greatest. They would have submitted to the wish of their Master, and honored the one whom He had chosen.
Instead of appointing one to be their head, Christ said to the disciples, "Be not ye called Rabbi;" "neither be ye called masters: for one is your Master, even Christ" (Matthew 23:8, 10, KJV).
Jesus' use of two different Greek words shows that Peter was called a stone, in contrast to the boulder of a rock upon which the church was to be built, which is Christ, the chief cornerstone (see Ephesians 2:20).