What is the rock in Matthew 16:18 upon which Jesus will build His church?

from the old testament

• The statement about the rock upon which Jesus said He would build His church is not found in the Old Testament. However, Isaish speaks about a coming “cornerstone,” namely the Messiah (Isaiah 28:16, c.f., Psalm 118:22). In the New Testament, Peter applies this passage to Jesus.

from the new testament

• In Matthew 16:18, Jesus uses a play on words when He said, “you are Peter and upon this rock I will build my church.” In Greek, Peter’s name means “rock.” This play on words has led some to conclude that Jesus was saying that Peter, the person, was a foundational “rock” upon which Jesus would build His church. Later in church history, this misunderstanding resulted in the Roman Catholic Church elevating Peter, calling him the first pope in a long line of popes.
• However, Peter’s own words show that he did not view himself that way. He said that Jesus was the “living stone” and the “cornerstone” of the church (1 Peter 2:4-7). He did this by applying Old Testament passages like Isaiah 28:16 which spoke about the Messiah (translated as “Christ,” in the New Testament) to Jesus. A “cornerstone” was a rock used in ancient construction that was laid first, ensuring the building would be constructed correctly. Therefore, Peter was saying that Jesus was the church’s foundation.
• Paul, in 1 Corinthians 3:11, also said that there is no other foundation than Jesus (c.f., Ephesians 2:19-20). Paul was arguing against a problem in the Corinthians church where some were claiming that their relationship with Paul elevated their status as a Christian. He wrote to tell them that it is God, not he—nor any other man—who causes the growth in the church (1 Corinthians 3:5-9). Rather than being the foundation, Paul said that his contribution was laying down the foundation, which was Jesus (1 Corinthians 3:10). By that he meant that he had faithfully declared to them who Jesus was.
• Paul considered Peter his equal, not a superior. In fact, Paul had to publicly rebuke Peter because he was leading others to sin by eating with only other Jews at times (Galatians 2:11-21). This shows that Paul (and the other Apostles by extension) did not consider Peter as having an elevated position in the church that placed him in authority over them, but that he was an equal with them, able to error, and subject to rebuke when he did.

implications for today

Jesus commended Peter for his declaration that Jesus is the Christ and Son of God. Peter’s right understanding was contrary to what others thought about Jesus (see, Matthew 16:14). There is only one way to salvation (John 14:6), which requires a true confession about who Jesus is and what He did (Romans 10:9). Ever since Jesus ascended, He has been faithfully building His church through the proclamation of who He is, which started with Peter’s first public sermon (Acts 2:14-36).

Like Peter experienced in his day, we also live in a world that has many different, and wrong views of Jesus. Those views range from saying that He was merely a really good teacher to saying that He was a well-intentioned but misguided fanatic. However, none of those views are true confessions about Jesus. Those wrong beliefs about Jesus cannot save someone. Only those with a true knowledge and confession of Jesus are added to the church. As believers go out, we have a mission to declare who the real Jesus is (Matthew 28:19-20). Jesus has promised that some will hear the Gospel and start to follow Him. The church is still being built by Jesus through the proclamation of who He is!