Petra – Peter rock
Matthew 16:18 - http://bible.cc/matthew/16-18.htm
Jesus said that Peter was *petros*(masculine) and that on this *petra*(feminine) He would build His church.
Greek: 4074 Pétros (a masculine noun) – properly, a stone (pebble), such as a small rock found along a pathway. 4074 /Pétros (”small stone”) then stands in contrast to 4073 /pétra (”cliff, boulder,” Abbott-Smith).
“4074 (Pétros) is an isolated rock and 4073 (pétra) is a cliff” (TDNT, 3, 100). “4074 (Pétros) always means a stone . . . such as a man may throw, . . . versus 4073 (pétra), a projecting rock, cliff” (S. Zodhiates, Dict).
4073 pétra (a feminine noun) – “a mass of connected rock,” which is distinct from 4074 (Pétros) which is “a detached stone or boulder” (A-S). 4073 (pétra) is a “solid or native rock, rising up through the earth” (Souter) – a huge mass of rock (a boulder), such as a projecting cliff.
4073 (petra) is “a projecting rock, cliff (feminine noun) . . . 4074 (petros, the masculine form) however is a stone . . . such as a man might throw” (S. Zodhiates, Dict).
It’s also a strange way to word the sentence that He would call Peter a rock and say that on this I will build my church instead of *on you* as would be grammatically correct in talking to a person.
There is no support from the original Greek for the idea that Jesus meant Peter to be that which He was going to build His church on. The nouns are not the same as one is feminine and the other masculine and denote different objects.
Actually, freeper Paisan provided the correct response.
Peter’s preeminent position among the apostles was symbolized at the very beginning of his relationship with Christ. At their first meeting, Christ told Simon that his name would thereafter be Peter, which translates as "Rock" (John 1:42). The startling thing was that—aside from the single time that Abraham is called a "rock" (Hebrew: Tsur; Aramaic: Kepha) in Isaiah 51:1-2—in the Old Testament only God was called a rock. The word rock was not used as a proper name in the ancient world. If you were to turn to a companion and say, "From now on your name is Asparagus," people would wonder: Why Asparagus? What is the meaning of it? What does it signify? Indeed, why call Simon the fisherman "Rock"? Christ was not given to meaningless gestures, and neither were the Jews as a whole when it came to names. Giving a new name meant that the status of the person was changed, as when Abram’s name was changed to Abraham (Gen.17:5), Jacob’s to Israel (Gen. 32:28), Eliakim’s to Joakim (2 Kgs. 23:34), or the names of the four Hebrew youths—Daniel, Hananiah, Mishael, and Azariah to Belteshazzar, Shadrach, Meshach, and Abednego (Dan. 1:6-7). But no Jew had ever been called "Rock." The Jews would give other names taken from nature, such as Deborah ("bee," Gen. 35:8), and Rachel ("ewe," Gen. 29:16), but never "Rock." In the New Testament James and John were nicknamed Boanerges, meaning "Sons of Thunder," by Christ, but that was never regularly used in place of their original names, and it certainly was not given as a new name. But in the case of Simon-bar-Jonah, his new name Kephas (Greek: Petros) definitely replaced the old.
When he first saw Simon, "Jesus looked at him, and said, ‘So you are Simon the son of John? You shall be called Cephas (which means Peter)’" (John 1:42). The word Cephas is merely the transliteration of the Aramaic Kepha into Greek. Later, after Peter and the other disciples had been with Christ for some time, they went to Caesarea Philippi, where Peter made his profession of faith: "You are the Christ, the Son of the living God" (Matt. 16:16). Jesus told him that this truth was specially revealed to him, and then he solemnly reiterated: "And I tell you, you are Peter" (Matt. 16:18). To this was added the promise that the Church would be founded, in some way, on Peter (Matt. 16:18).
Then two important things were told the apostle. "Whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven" (Matt. 16:19). Here Peter was singled out for the authority that provides for the forgiveness of sins and the making of disciplinary rules. Later the apostles as a whole would be given similar power [Matt.18:18], but here Peter received it in a special sense.
Peter alone was promised something else also: "I will give you the keys of the kingdom of heaven" (Matt. 16:19). In ancient times, keys were the hallmark of authority. A walled city might have one great gate; and that gate had one great lock, worked by one great key. To be given the key to the city—an honor that exists even today, though its import is lost—meant to be given free access to and authority over the city. The city to which Peter was given the keys was the heavenly city itself. This symbolism for authority is used elsewhere in the Bible (Is. 22:22, Rev. 1:18).