When Jesus gave Peter his name (rock) what is the significance that he then said upon a ‘different’ kind of rock he would build his church?

When Jesus gave Peter his name (rock) what is the significance that he then said upon a ‘different’ kind of rock he would build his church?

The Petra / Petros difference does not seem to carry as much significance as some might suggest.

Matthew 16:17-18 And Jesus answering said to him, Happy art thou, Simon Bar-Jona, because flesh and blood did not reveal it to thee, but my Father who is in the heavens.And I also say to thee, that thou art a rock, and upon this rock I will build my assembly, and gates of Hades shall not prevail against it;

• YLT (Young’s literal translation)

In the context of Matthew 16 we see Jesus rebuking the disciples for not having much faith.

Matthew 16:11 How is it that ye do not understand that I spake it not to you concerning bread, that ye should beware of the leaven of the Pharisees and of the Sadducees?

Jesus, after they had traveled a bit, then asks them;

Matthew 16:13 When Jesus came into the coasts of Caesarea Philippi, he asked his disciples, saying, Whom do men say that I the Son of man am?

This might be called a real test of faith. This cuts to the core of what is important. Peter passes this test and is declared to have this knowledge directly from God as a result (verse 17).

The case can be made that the “rock” being described in verse 18 is the “rock” of faith. Later Peter uses the illustration of faith being a stone built into a house.

1 Peter 2:5 Ye also, as lively stones, are built up a spiritual house, an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ.

As another answer alluded to, Jesus almost certainly was speaking Aramaic, not Greek when he spoke these words. As such, it is probably a mistake to automatically assume that Jesus was making a philosophical point by using two different words based on the Greek. Instead, we should see what explanations are available as to how the Greek came from the original Aramaic and decide which is best.

Meaning of Πέτρος

To help us decide, we should first determine what, if any difference there is between the meaning of Πέτρος (petros, translated as "Peter") and πέτρα (petra, translated "rock"). First, on πέτρα , A Greek-English Lexicon of the New Testament and Other Early Christian Literature (BDAG) says the usual meaning is "bedrock or massive rock formations". So, most often the writer/speaking will have something like an exposed rock formation in mind, not an individual stone. Matthew 16:18 is classified under this meaning by BDAG. A less common meaning is "a piece of rock". That is, what an English speaker typically thinks of when they hear "rock". Either way, "rock" is a reasonable translation.

Now, on to πέτρος. According to BDAG, the word is unattested to as a name from before the New Testament. Instead, it was probably created (as a name) in Greek as the equivalent of the Aramaic כיפא (Kepa), which also appears in the New Testament as Κηφᾶς (Kephas), and means "rock". There is no connotation of "small rock" in the Aramaic.

It is sometimes claimed, like in the accepted answer, that πέτρος meant a pebble or small stone during Jesus' time. This claim almost certainly untrue. It is true that in some Attic Greek poetry πέτρος was used to mean a small rock, but it could also refer to bigger rocks in period writing. More importantly, the New Testament was not written in Attic Greek, but rather Koine Greek.

In Koine Greek, this specialized use of πέτρος is unattested. Furthermore, two other words existed that could have been used to draw a distinction between the size of the "rocks". The word λίθος (lithos) was the most common word for ordinary rocks and stones and the word ψῆφος (psephos) could be used to describe a pebble. If Jesus or Matthew wanted to make a point about the size of the "rock", he chose an odd way to do it.

A simple explanation

Why then is the word for Peter πέτρος? The answer is actually quite simple - πέτρα is a feminine word and men cannot have grammatical feminine names in Koine Greek. Πέτρος is just the same word with a masculine ending.

Given this simple fact, and the fact that Simon was already given the name Cephas at his initial calling (John 1:42), it is far more natural to conclude that the word variation has no special significance than to conclude there is a special meaning to be understood here.

Commentaries

Here is a sampling of (mostly Protestant) commentaries that back this understanding:

• Bengal's Gnomen: "πέτρος elsewhere signifies a stone; but in the case of Simon, a rock. It was not fitting that such a man should be called Πέτρα, with a feminine termination; on the other hand, St Matthew would gladly have written ἘΠῚ ΤΟΎΤῼ Τῷ ΠΈΤΡῼ, if the idiom would have allowed it; wherefore these two, ΠΈΤΡΑ and ΠΈΤΡΟς, stand for one name and thing, as both words are expressed in Syriac by the one noun, Kepha."

• Ellicott's Commentary for English Readers: "the words in the Greek differ in gender, πέτρος and πέτρα, but were identical in the Aramaic, which our Lord probably used"

• Expositor's Greek Testament: "πέτρος, τέτρᾳ, a happy play of words. Both are appellatives to be translated “thou art a rock and on this rock,” the two being represented by the same word in Aramaean (כֵיפָא). Elsewhere in the Gospels Πέτρος is a proper name, and πέτρα only is used in the sense of rock"

• Gill's Exposition of the Entire Bible: "he was rightly called Peter, or Cephas, by him, when he first became a follower of him, which words signify the same thing, a rock, or stone;"

• The Jamieson-Fausset-Brown Bible Commentary: "As 'Peter' and 'Rock' are one word in the dialect familiarly spoken by our Lord—the Aramaic or Syro-Chaldaic, which was the mother tongue of the country—this exalted play upon the word can be fully seen only in languages which have one word for both. Even in the Greek it is imperfectly represented."

• Pulpit Commentary: "In classical Greek, the distinction between πέτρα and πέτρος is well known - the former meaning 'a rock,' the latter 'a piece of rock,' or 'a stone.' But probably no such distinction is intended here, as there would be none in Aramaic."

Of these, only Ellicott's considers the possibility of a meaningful distinction between Πέτρος and πέτρα to be viable writing:

• "on the other, the possibility that [Jesus] may have used the Greek words, or that the Evangelist may have intended to mark the distinction which he felt by the use of the two words... On the assumption of a distinction there follows the question, What is the rock? Peter’s faith (subjective)? or the truth (objective) which he confessed? or Christ Himself? Taking all the facts of the case, the balance seems to incline in favour of the last view."

I am not aware of any other commentary that considers it possible.

Ok, so the reality is that there is the appearance of a Discrepancy of sorts in the bible, Peter being called "Pétros", and The church being built on "pétra."

As a Catholic heres how we interpret this scripture.

the Aramaic word kēpā' meaning rock and transliterated into Greek as Kēphas is the name by which peter is called in the Pauline letters (1 Cor 1:12; 3:22; 9:5; 15:4; Gal 1:18; 2:9, 11, 14) except in Gal 2:7-8 ('Peter'). It is translated as Petros ("Peter") in Jn 1:42. The presumed original Aramaic of jesus' statement would have been in English, "You are the Rock (kēpā') and upon this rock (kēpā') I will build my church." The Greek text probably means the same, for the difference in gender between the masculine noun petros, the disciples new name, and the feminine noun petra (rock) may be dew to the unsuitability of using a feminine noun as the proper name of a male.Although the two words were generally used with the same meaning, "rock" ...

Thats found in the note on Mt 6:18 (NAB) in my bible

So another words Jesus used the same word to refer to peter and 'the rock,' which is why Catholics believe that Jesus "built the church" on Peter, and the other popes. Of course, Faith is a gift given by God, and if it wasn't for that faith, Peter, and the rest of the Papacy, and their flock could have never started the church that we know today. So it does make sense, in a way, to say that Peter is a 'little rock' and upon the 'Big rock', the faith Of the head of the body of Christ, (which is given to peter) Jesus builds his church.