Matthew 16:18 And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it.
One frequent rebuttal of the claim that this verse is stating that the church will be built upon Peter is the fact that although there is some similarity between the Greek words for "Peter" and "rock," nevertheless they are different Greek words.
I've seen a number of attempted counter-arguments from those supporting the papacy (which, in a word, are properly called "papists"). The papists argue:
1) While the words are different words in Greek, the words are the same in Aramaic and Jesus was speaking Aramaic, not Greek. This is the "speculative reconstruction of the original" argument.
This is probably one of the better objections. There are, however, several reasonable rebuttals:
a) We have no good reason to suppose that the statement was made in Aramaic rather than in Greek. In other words, we don't know that the text we have is a translation. Although Jesus doubtless knew Aramaic, nevertheless Greek was also spoken in Judea at the time, and there is no particular reason to favor one language over the other in this instance (aside from wishful thinking on the part of the papists). Since Jesus and his earthly parents had lived in Egypt for a time, it would not have been surprising if they knew Greek - since it was the international language of the day.
b) Even if the original language spoken had been Aramaic, the inspired words penned by Matthew were in Greek. Although a few people have tried to argue that Matthew was originally written in Aramaic, the historical consensus is that the original language was Greek. Furthermore, this historical consensus is confirmed by the translation at Matthew 1:23:
Matthew 1:23 Behold, a virgin shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us.
The provision of this translation provides evidence that the original was Greek. If the original was in Aramaic, there would have been no need to provide a translation of the name "Emmanuel," and there would have been no clue to the translator from Aramaic to Greek to insert such a translation rather than simply transliterating the name.
2) Other times, the papists argue that πετρος (petros = Peter) and πετρα (petra = rock) are used because one is the right word for a man and the other is the right word for a rock. Sometimes this is phrased as saying that Jesus couldn't have called Simon "Petra" because that would have been like calling him "Mary" or some other feminine name. Alternatively, they say that Jesus couldn't have said that he was going to build his church upon "petros" because that wouldn't be the right Greek word for "rock." I call this the "God is boxed-in by Greek" argument.
a) Although this argument may have some appeal, there is an obvious way Jesus could have avoided the Petros/petra distinction. Jesus could have said, "thou art Peter, and upon thee I will build my church." Jesus did not say this. Instead, Jesus said "thou art Peter, and upon this rock I will build my church."
For the "God is boxed-in by Greek" argument to work, one has to speculate that Jesus spoke the first half the sentence to Peter and the second half of the sentence about Jesus - he has to change audiences mid-sentence, even though (as though to avoid the papist misconception) Jesus begins the sentence by saying, "And I say also unto thee." Notice the "thee." That means that he is (again) addressing Peter, just as had been addressing Peter in the previous verse.
With this in mind, the most natural sense of Jesus' words is to understand "this rock" as referring to the same thing as Jesus had already referred to in the previous statement to Peter. Recall that Jesus' first response to Peter was:
Matthew 16:17 And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven.
The word "it" there in the center of the sentence is a word added by the translators to help convey the sense of the sentence. The "it" referenced (implicitly, in the original Greek) is Simon Peter's confession, "Thou art the Christ, the Son of the living God." This is what was not revealed to Simon Barjona by flesh and blood, but by God the Father. This rock is what the church will be built upon.
Interestingly, even the council of Trent acknowledged this interpretation of the text:
For which cause, this council has thought good, that the Symbol of faith which the holy Roman Church makes use of,--as being that principle wherein all who profess the faith of Christ necessarily agree, and that firm and alone foundation against which the gates of hell shall never prevail,--be expressed in the very same words in which it is read in all the churches.And again, later:
Let all, therefore, understand, in what order, and in what manner, the said Synod, after having laid the foundation of the Confession of faith, will proceed, and what testimonies and authorities it will mainly use in confirming dogmas, and in restoring morals in the Church.In both quotations, the emphasis has been added. It is worth noting that Trent foreclosed an argument that the symbol of faith is just one foundation by the use of the word "alone." But I digress.
The key to this first rebuttal is to note that Jesus' use of the third person makes more sense viewed as simply referring to someone other than Peter rather than as an audience switch mid-sentence.
b) In the second place, if Jesus had wanted to use a Greek word that would permit a direct relation between Simon and that upon which the church is built, Jesus could have surnamed him θεμέλιος (themelios = foundation), which is a masculine Greek noun.
What would have been interesting about this word is that in Revelation 21:14 the heavenly city is described has having walls with twelve foundations, in which the names of the twelve apostles are written. Paul likewise describes believers as being built on the foundation of the apostles and prophets. Paul is careful, however, to note that Jesus Christ himself is the chief corner stone. Likewise Peter himself, in exhorting his readers to the desire of the Word of God, states:
1 Peter 2:2-8
2As newborn babes, desire the sincere milk of the word, that ye may grow thereby: 3If so be ye have tasted that the Lord is gracious. 4To whom coming, as unto a living stone, disallowed indeed of men, but chosen of God, and precious, 5Ye also, as lively stones, are built up a spiritual house, an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ. 6Wherefore also it is contained in the scripture, Behold, I lay in Sion a chief corner stone, elect, precious: and he that believeth on him shall not be confounded. 7Unto you therefore which believe he is precious: but unto them which be disobedient, the stone which the builders disallowed, the same is made the head of the corner, 8And a stone of stumbling, and a rock of offence, even to them which stumble at the word, being disobedient: whereunto also they were appointed.
Notice that like Paul, Peter points to Jesus himself as the corner stone upon which the church is built. So, although Jesus could have performed a mid-sentence audience shift without introducing a distinction by surnaming Simon Themelios instead of Petros, nevertheless, Jesus did not do so - and Jesus' failure to do so is understandable in view of the other testimony of Scripture above, which describes Jesus as the cornerstone.
In fact, there is an even closer word than Themelios that Jesus could have picked: he could have picked λίθος (lithos - stone). But, again, it is Jesus himself that is the chief corner lithos in those verses above.
c) God is in control of all things. When Jesus wanted to pay the temple tax, he was able to arrange that the first fish Peter caught on a particular occasion would have in its mouth a particular coin that would be sufficient to pay the temple tax for both Peter and Jesus (Matthew 17:24-27). Furthermore, as Moses was reminded:
Exodus 4:11 And the LORD said unto him, Who hath made man's mouth? or who maketh the dumb, or deaf, or the seeing, or the blind? have not I the LORD?
So then, if God had wanted to, God could have arranged the Greek language to avoid the distinction provided in Matthew 16:18, if God had wanted to avoid that distinction. Since the distinction is there, it is reasonable to presume that the distinction is intentional. That is to say, God is not limited by human language.