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).
Its 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.
http://www.vatican.va/archive/ENG0015/__P1D.HTM
424 Moved by the grace of the Holy Spirit and drawn by the Father, we believe in Jesus and confess: 'You are the Christ, the Son of the living God.'8 On the rock of this faith confessed by St. Peter, Christ built his Church.9 "To preach. . . the unsearchable riches of Christ"10
What is your degree in.
Don't let the facts get in the way of a good rant or hissy fit.
It seems some FRomans think they know better than their own catechism. A trend here.