Peter did not receive his revelation from man, literally "flesh and blood" (compare Gal 1:16), a common expression for "mortals" or "humans" (as in 1 Cor 15:50; Eph 6:12; Heb 2:14; 1 Enoch 15:4; Mek. Pisha 1.120). Peter's understanding of Jesus' identity came by divine revelation (Mt 16:17; 11:25), undoubtedly including God's revelation through Jesus' miraculous acts (14:33; compare 15:22). This revelation of Jesus' identity was foundational for God's purposes in history.

Jesus then plays on Simon's nickname, Peter, which would be roughly the English "Rocky": Peter is rocky, and on this rock Jesus will build his church (16:18). Scholars have debated precisely what Jesus means by rock. Protestants, following Augustine and Luther, have sometimes contended that the rock in this passage is only Jesus himself (references in Cullmann 1953:162 n. 13). But by Jesus' day the Greek terms petros (Peter) and petra (rock) were interchangeable, and the original Aramaic form of Peter's nickname that Jesus probably used (k h phas) means simply "rock" (Cullmann 1953:18-19; Ladd 1974b:110; Carson 1984:368; France 1985:254; Blomberg 1992:252).

Further, Jesus does not say, "You are Peter, but on this rock I will build my church"; he says, And on this rock I will build my church. Jesus' teaching is the ultimate foundation for our lives (7:24-27; compare 1 Cor 3:11), but here Peter functions as the foundation rock like the apostles and prophets in Ephesians 2:20-21. Jesus does not simply assign this role to Peter arbitrarily, however; Peter is the "rock" because in this context he is the one who confesses Jesus as the Christ (Mt 16:15-16; Cullmann 1953:162; Ladd 1974b:110; C. Brown 1978:386). Others who share his proclamation also share his authority in building the church (18:18 with 16:19).