16:18

You are Peter, and on this rock: The Greek word peʹtros in the masculine gender means “a piece of rock; a stone.” Here it is used as a proper name (Peter), the Greek form of the name Jesus gave Simon. (Joh 1:42) The feminine form peʹtra is rendered “rock,” and it may denote bedrock, a cliff, or a mass of rock. This Greek word also occurs at Mt 7:24, 25; 27:60; Lu 6:48; 8:6; Ro 9:33; 1Co 10:4; 1Pe 2:8. Peter evidently did not view himself as the rock on which Jesus would build his congregation, since he wrote at 1Pe 2:4-8 that Jesus was the long-foretold “foundation cornerstone,” chosen by God himself. Similarly, the apostle Paul referred to Jesus as the “foundation” and “the spiritual rock.” (1Co 3:11; 10:4) So Jesus was evidently using a play on words, saying in effect: ‘You, the one I called Peter, a Piece of Rock, have discerned the true identity of the Christ, “this rock,” the one who will serve as the foundation of the Christian congregation.’

congregation: This is the first occurrence of the Greek term ek·kle·siʹa. It comes from two Greek words, ek, meaning “out,” and ka·leʹo, meaning “to call.” It refers to a group of people summoned or called together for a particular purpose or activity. (See Glossary.) In this context, Jesus foretells the formation of the Christian congregation, made up of anointed Christians, who as “living stones” are being “built up into a spiritual house.” (1Pe 2:4, 5) This Greek term is frequently used in the Septuagint as an equivalent of the Hebrew term rendered “congregation,” which often refers to the entire nation of God’s people. (De 23:3; 31:30) At Ac 7:38, the Israelites who were called out of Egypt are referred to as a “congregation.” Similarly, Christians who are “called . . . out of darkness” and “chosen . . . out of the world” make up “the congregation of God.”​—1Pe 2:9; Joh 15:19; 1Co 1:2.

the Grave: Or “Hades,” that is, the common grave of mankind. (See Glossary, “Grave.”) The Bible speaks of the dead as being within “the gates of death” (Ps 107:18) and “the gates of the Grave” (Isa 38:10), that is, subject to the power of death. Jesus promises victory over the Grave, meaning that “the gates” of the Grave will open to release the dead by means of a resurrection. His own resurrection confirmed the truthfulness of his promise. (Mt 16:21) Because the congregation is built on Jesus, the one who can release its members from death, it cannot be overpowered by or permanently restrained by the Grave.​—Ac 2:31; Re 1:18; 20:13, 14.