So two questions must be addressed. What was the rock upon which JESUS will build HIS church. And how is Jesus' church built.<quoted text>
Jesus said (not ME writing);
18 And I say to you: That you are Peter; and upon this rock I will build my church, and the gates of hell shall not prevail against it. 19 And I will give to you the keys of the kingdom of heaven. And whatsoever you shall bind upon earth, it shall be bound also in heaven: and whatsoever you shall loose on earth, it shall be loosed also in heaven.
Let's look first at how Jesus builds His church. How does the church grow? It grows as people(who are the church) are added. And how are these people added? They are added when they come to believe in and recieve Him as who He claims to be; the 'Saviour of the World'.
By understanding this basic principle we can get a better understanding of what the 'ROCK' was that Jesus was referring to. The rock is the 'profession' that Peter had just made in response to Jesus' question of 'Who do men say that I am....and who do YOU say that I am.' Certainly Peter does not show himself to be a rock in his denial and cursing of Jesus. Jesus builds HIS CHURCT one person at a time and they come to have faith in Him and 'profess' that faith.