Sorry. Even catholics prove that's not correct. (protestants knew it ever since , well, ever)...
http://www.reachingcatholics.org/rock.html
excerpt:
"Upon This Rock
James McCarthy
In the Gospel of Matthew we read:
Now when Jesus came into the district of Caesarea Philippi, He began asking His disciples, saying, "Who do people say that the Son of Man is?" And they said, "Some say John the Baptist; and others, Elijah; but still others, Jeremiah, or one of the prophets." He said to them, "But who do you say that I am?" And Simon Peter answered and said, "Thou art the Christ, the Son of the living God." And Jesus answered and said to him, "Blessed are you, Simon Barjona, because flesh and blood did not reveal this to you, but My Father who is in heaven. And I also say to you that you are Peter, and upon this rock I will build My church; and the gates of Hades shall not overpower it." —Matthew 16:13-18
The Roman Catholic Church interprets Jesus here to say, "You are Peter, and upon you, Peter, I will build My church." Peter would be the rock upon which the Church would be built [552, 586, 881]. He would be the "prince of all the apostles and visible head of the whole church."
There are several problems with this interpretation. The first is that someone reading Matthew’s Gospel in Greek, the original language of the New Testament, would not have immediately concluded that Peter was the rock. In the Gospel of Matthew, when Jesus said to Simon, "You are Peter, and upon this rock I will build My church" (Matthew 16:18), His choice of words was significant. Though Peter’s name means rock (petros), Jesus did not say, "You are Peter (Petros), and upon this rock (petros) I will build my church." What He said was, "You are Peter (Petros), and upon this rock (petra) I will build My church."
The word Jesus chose to use for rock, petra, is a feminine noun that refers to a mass of rock. The New Testament uses this word in Matthew 7:24,25 to refer to the bedrock upon which a wise man built his house. Petra is also found later in Matthew’s Gospel with reference to Jesus’ tomb, which workers had carved out of solid rock (Matthew 27:60).
Peter’s name, Petros, on the other hand, is masculine in gender and refers to a boulder or a detached stone. Greek literature also uses it of a small stone that might be picked up and thrown.
What Jesus said to Peter could be translated, "You are Stone, and upon this bedrock I will build My church." His choice of words would indicate that the rock on which the church would be built was something other than Peter.
Anyone reading the Gospel of Matthew in the original Greek language would have noticed the difference. The reader would have had to pause and decide what was meant by "upon this rock" (Matthew 16:18). The reader would not immediately have equated the rock (petra) with Peter (Petros), because the words are different.
To determine the best interpretation, the reader would have had to look more closely at the context. This is the second and greatest weakness with the Roman Catholic interpretation: It fails to give proper emphasis to the context.
The context of Matthew 16:13-20 is not about Peter; it is about Jesus. It starts with a question that Jesus raises about His identity: "Who do people say that the Son of Man is?" (Matthew 16:13). It reaches a climax with Peter’s declaration: "Thou art the Christ, the Son of the living God" (Matthew 16:16). It concludes with the Lord warning His disciples "that they should tell no one that He was the Christ" (Matthew 16:20).
When Peter correctly answered Jesus’ question as to His identity, the Lord remarked, "Blessed are you, Simon Barjona, because flesh and blood did not reveal this to you, but My Father who is in heaven" (Matthew 16:17). Peter’s insight into Jesus’ true identity was a revelation from God. In this context, Jesus, making a play on words, says, "You are Peter, and upon this rock I will build My church" (Matthew 16:18).
The context argues for interpreting "this rock" as referring back to the revelation and its content. In other words, the Lord Jesus as "the Christ, the Son of the living God" (Matthew 16:16) would be the solid rock upon which the Christian faith would rest. Every doctrine and practice would be founded upon Him. Every true believer would hold to a common conviction: Jesus is "the Christ, the Son of the living God" (Matthew 16:16).
The cultural context of the passage also supports interpreting "this rock" as referring to Jesus in His identity as the Son of God. Matthew wrote his Gospel for a Jewish audience. He expected his readers to be familiar with Old Testament imagery.
How would a Jewish reader interpret "upon this rock"? G. Campbell Morgan answers, "If we trace the figurative use of the word rock through Hebrew Scriptures, we find that it is never used symbolically of man, but always of God." For example:
There is no one holy like the Lord; Indeed, there is no one besides Thee, Nor is there any rock like our God. —1 Samuel 2:2
For who is God, but the Lord? And who is a rock, except our God? —Psalm 18:31
Is there any God besides Me, Or is there any other Rock? I know of none. —Isaiah 44:8
The wider context of the New Testament also confirms that Jesus, not Peter, is the rock. For example, Peter himself wrote of Christ as a rock (petra):
For this is contained in Scripture: "Behold I lay in Zion a choice stone, a precious corner stone, and he who believes in Him shall not be disappointed." This precious value, then, is for you who believe. But for those who disbelieve, "The stone which the builders rejected, this became the very corner stone," and, "A stone of stumbling and a rock (petra) of offense." —1 Peter 2:6-8
Paul also refers to Christ by the Greek word petra. In Romans he wrote of Christ as "a rock (petra) of offense" (Romans 9:33) over which the Jews had stumbled. In First Corinthians he wrote of a spiritual rock encountered by Israel in the wilderness. He identified that rock, saying, "...and the rock (petra) was Christ" (1 Corinthians 10:4).
Interpreting Christ as the rock upon which the church would be built also harmonizes well with other statements in Scripture. Paul warned, "No man can lay a foundation other than the one which is laid, which is Jesus Christ" (1 Corinthians 3:11). Here he emphasizes that Christ is the foundation upon which the church is built. In Ephesians, Paul speaks of the church as "having been built upon the foundation of the apostles and prophets, Christ Jesus Himself being the corner stone" (Ephesians 2:20). Here Paul pictures Christ as the principal stone and the apostles and prophets as secondary stones...." (more at site/link)