of rocky ground is sometimes suggested, but Greek use in antiquity seems to have been less precise. The word "church" (ekklesia in Greek), as used here, appears in the Gospels only once more, in Matthew 18:17, and refers to the community of believers at the time. The "gates of hell" (of Hades) refers to the underworld, and the abode of the dead, and refers to the powers opposed to God not being able to triumph over the church. The keys of the kingdom of heaven refer to the metaphor of the Kingdom of Heaven being a "place to be entered" as also used in Matthew 23:13, where the entrance to it can be shut. Peter's authority is further confirmed by: "Whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven." As discussed below, various Christian denominations have assigned different interpretations to the authority granted in this passage. Jesus silencing the disciples All three of the Synoptic Gospels end the account with Jesus telling the disciples not to reveal that he was the Messiah to anyone — an instance of the motif of the Messianic Secret. Denominational issues Interpretations Various Christian denominations interpret Matthew 16:18 in different ways. Although most denominations agree that the statement applies to Peter, they diverge on their interpretations of what happens after Peter. In the Roman Catholic Church, Jesus' words "upon this rock I will build my church" are interpreted as the foundation of the doctrine of the papacy, whereby the Church of Christ is founded upon Peter and his successors, the Bishops of Rome. Jesus' next statement, "and the gates of hell shall not prevail against it." are interpreted as the foundation of the doctrine of papal infallibility. Some Protestants believe that the verse states that Peter was the foundation stone of the Church, but do not accept that it applies to the continuous succession of popes, as the Bishops of Rome. The statement "and the gates of hell shall not prevail against it" is usually taken to mean that the Church will never become extinct. Some Protestant evangelical groups adhere to the interpretation that it is Peter's "confession" itself that is "the rock on which will be built the Church of Jesus", i.e., the church will be built on Jesus alone as the foundation stone of his church. This interpretation usually