What is the meaning of Jesus’ words in Matthew 16:18?
“When we examine the words petros, (Peter) and petra (rock) we note immediately that they are not related. For the former is a masculine gender, and the latter is a feminine gender. The word petra means a ledge rock such as the ledge rock upon which the city of Caesarea Philippi rested. It was a foundation rock. A petros was a little stone such as might be broken off a petra. It partook of the nature of the petra, but it was not a petra.
Now to what does petra refer? Some hold that it refers to Peter, not as a person, but as a type of all who make the confession which he made. Others relate it to the faith as revealed in the confession. But either of these leaves much to be desired. The overall teachings of the New Testament regard Jesus Himself as the foundation of the church (cf. 1 Cor. 3:10-11).
It would appear, therefore, that petra refers to Christ Himself. He is the rock upon which the church will be built. And it will be built out of the petroi (stones) which partake of the nature of the petra through their confessions of faith in Jesus as “the Christ, The Son of the living God.” This may well have been in the mind of Peter when he wrote, “Ye also, as living stones (lithoi) are built up an spiritual house…” (1 Peter 2:5).
What did Jesus mean by the keys and loosing and binding in Matthew 16:19?
The keys in a house were entrusted to a slave who was the “steward” of the owner. Furthermore, the phrase “binding…loosing” was a Rabbinical term relating to the scribe as a teacher. In Rabbinical language “to bind” was “to forbid,” “to loose” was “to permit.” Keys are for locking or opening doors. So the “keys of the kingdom of heaven” would refer to either shutting its doors to prevent entrance or else opening its doors to permit it. What is it which constitutes the right to enter into the kingdom of heaven? It is one’s confession of the King as “the Christ, the Son of the living God.” In essence, therefore, this involves the gospel, the life, death, and resurrection of Jesus from the dead. These elements of the gospel are not yet clearly defined in the minds of the apostles. But Jesus is looking beyond the events to their proclamation through the ages. So He is here committing to His church the gospel which it is to preach throughout the world until the end of the age. The church can either bind or loose it.
And this thought introduces again the meaning of binding and loosing in terms of the Christian gospel. In the Greek text of “shall be bound…shall be loosed” the verbs are what is called the periphrastic future perfect passive. This form expresses an action which took place in the past but whose effect is still existing in the present, and will continue to be in effect in the future. Literally, “shall have been bound…shall have been loosed.” In effect, the binding and loosing were in heaven, are still there, and will continue to be there. And the passive voice speaks of this binding and loosing as being done by one other than man on earth, or by God Himself.
So what did Jesus actually say? He said that heaven has already decreed that if we bind the gospel on earth, it is bound and stands bound in heaven. If we loose the gospel on earth, it is loosed and stands loosed in heaven. Heaven or God has decreed that men shall be saved by hearing and believing the gospel. If we bind it on earth by failing to proclaim it, heaven has no other way by which men shall be saved. But if we loose it on earth men will hear, and those who believe it shall be saved.”[1]
[1] Herschel H. Hobbs, An Exposition of The Gospel of Matthew, Grand Rapids, Michigan: Baker Book House, pp. 218, 221-222.