While most modern critics will accept that Jesus existed and intended that his mission would be carried on in some form, it is when we come to this matter of juridical authority and structure that some drift away from the historical record. Therefore, it is vital to understand the role of Peter among the first Christians.
The famous “rock” text from Matthew, cited above, has been the subject of dispute since the rise of Protestantism in the sixteenth century. Some commentators have held that when Christ promised to build his Church upon the “rock,” he was referring to the rock of Peter’s faith, which Peter had professed in the preceding verse (“You are the Messiah, the Son of the Living God”). But the entire passage makes clear that Christ simply used the occasion of Peter’s profession to declare that Peter himself was the “rock,” as is signified by Christ’s telling and obviously deliberate choice of the name “Peter” for this Simon Barjona (Son of John): “Thou art Peter”, which in Greek is a proper name formed from the word rock. Not without reason, therefore, do some translations read, “Thou art the Rock, and upon this rock I will build my Church.” This interpretation is confirmed in St. John’s Gospel where our Lord tells Simon that He is changing his name to Cephas, which is the Aramaic word for rock (Jn 1:42). What Jesus is doing here can only be compared to the name changes in the Old Testament which attend the appointment to positions of leadership over God’s people (Abram-Abraham, Jacob-Israel), and in which the meaning of the new name always conveys something about the kind of role the leader is to play.
The giving of the keys has likewise been disputed, but with far less reason even than the “rock” text, the arguments revolving around whether Peter received the keys corporately or singularly. But in fact, he didn’t receive them at all in this text (the future is used: “to you I will give the keys”), and the fulfillment of this promise comes logically after the Resurrection when Our Lord was preparing to return to the Father, in the dramatic threefold parallel to Peter’s denial: “Do you love me, Peter? … Feed my sheep.” (Jn. 21:15-17). Likewise, Christ prayed especially for Peter so that he might “confirm his brethren” (Lk 22:32).
When Christ gave Peter the “Keys”, this, according to long custom of the Jews and other peoples, symbolized the conferring of authority (cf Is. 22:22; Ap 3:7). He was given complete power to bind and to loose”, which means to forbid and permit, and to do so in such a way that God’s own authority is thereby committed. Thus Peter is called the Vicar of Christ, the one who visibly heads the Church in the name of Christ.