PROMISE OF INFALLIBILITY
Two important things were told the apostle: “Whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven” and “I will give you the keys of the kingdom of heaven” (Mt 16:19). Here Peter was singled out for the authority that provides for the forgiveness of sins and the making of disciplinary rules. Later the apostles as a whole would be given similar power (Mt 18:18), but here Peter received it in a special sense.
And Peter alone was promised the keys.
Let us speak of the first promise.
Christ says:”Whatever you bind, Peter, will be bound in heaven”. [Peter is the binding authority, since the Church is “the pillar of truth” (I Tim. 3:15), not Scripture.]
Now, we know that God “does not lie” (Tit. 1:2), which means that He cannot confirm a lie either.
Therefore, this verse proves that Peter speaks infallibly. Which, interestingly enough, he did authoritatively at that very moment (Mt 16:16), in the midst of a multiplicity of opinions, by proclaiming Christ divinity, under a special inspiration of God.
THE KEYS OF THE KINGDOM
In the Eastern kingdoms, the sovereign king of the realm would delegate the authority and administration of his kingdom to a steward (also called “vizier” or “majordomo”), who managed the kingdom—virtually ruling for the king- especially in his absence. The person who was “over the house” had the whole of the domestic affairs of the sovereign under his superintendence. He made decisions which carried royal authority and could not be appealed (cf. Gen 24:2; 39:4; I Kg 3:1; 4:1–6; 16:9; 18:3–16; 18:3; II Kg 10:5; 15:5; II Chron. 28:7; Esther 3:1–2; 8:1–2).
Israel imitated the nations around her (especially Egypt) and adopted their forms of government (I Sam. 8:5). The image of the kingdom keys (Mt 16:19) was therefore a well known figure to Our Lord’s listeners, because in ancient Israel, for centuries, there was a divine kingdom established by God with the covenant with David (II Sam. 7:12–13). And we know that the key holder was the son of David, the king of Israel, who held “the keys of the House of David” (Is. 22:22). He was the key holder, as the king of Israel, but he would entrust to the Prime Minister the keys for administration. Just as the master of the house would set the chief steward over all the household possessions, so the king, as the one who holds the keys, would give them to his Prime Minister.
So Jesus, “the Son of David” (Lk 1:30–31), the royal heir of the Davidic Kingdom, the key holder (Rev. 1:18; 3:7), quoting almost verbatim from this passage in Isaias, is installing Peter as a form of chief steward or Prime Minister by giving him the keys to the kingdom. He is raising Peter up as a father figure to the household of faith (Is. 22:21; I Tim. 3:15), to lead them and guide the flock (John 21:15–17). Under the new and eternal covenant (I Cor. 11:25; Heb 13:20) extended to all men, Christ the King, to Whom “all power in heaven and on earth has been given” (Mt 28:18), puts Peter as his Prime Minister to govern the whole world in his absence.