Will you please explain Matthew 16:18?

Peter’s words in Matt. 16:16, “You are the Christ, the Son of the Living God,” brought commendation from the Lord. The Lord then called Peter blessed in verse 17 because he had come to a correct conclusion about the person of Christ and because great blessing would be brought into his life. The Lord added, however, this was not a conclusion Peter had determined by his own ability or that of others. God, the Father in heaven, had revealed it to him. Peter, then, was living up to his name which means “rock” for he was demonstrating himself to be a rock. When the Lord and Peter first met, Jesus had said Simon would be named Cephas (Aram for “rock”) or Peter (Gr. for “rock”; John 1:41-42).

Peter’s declaration about Messiah’s person led to a declaration of Messiah’s program by the Lord. Peter (Petros, a masculine noun and referring to a smaller rock, a boulder) was strong like a rock, but Jesus added that on this rock (petra, a feminine noun, which referred to a huge rock or a large mass of rock) He would build His church. Because of this change in Greek words (from petros to petra), many conservative scholars believe that Jesus is now building His church on Himself. Others hold that the church is built on Peter and the other apostles as the building’s foundation stones (be sure to see Eph. 2:20; Rev. 21:14). Still other scholars say that the church is built on Peter’s testimony. It seems best to understand that Jesus was praising Peter for his accurate statement about Him, and was introducing His work of building the church on Himself (1 Cor. 3:11). The idea that Christ was declaring Peter as the foundation separate from all the other apostles is contrary to Eph. 2:20 which clearly teaches that the church is built on the foundation of all the apostles and prophets with Christ being the chief cornerstone.