After changing Simon’s name to Peter, Jesus did something else that made Peter’s important position in the kingdom even more obvious. Jesus gave Peter “the keys to the kingdom” and the power to “bind and loose” (Mt. 16:19).
To understand the rich symbolism of the keys, we need to see how they were used in the Davidic kingdom of the Old Testament.
The key of the house of David symbolized the administrative authority of the “master of the palace” who is “over the household.” This person would be the king’s highest ranking official in the royal court, known as the al bayyit or prime minister, who acts with the king”s authority.
Let’s look at this role in the Old Testament. [more]Check out Isaiah 22:15-23:
 Thus says the Lord GOD of hosts, “Come, go to this steward, to Shebna, who is over the household, and say to him:
 What have you to do here and whom have you here, that you have hewn here a tomb for yourself, you who hew a tomb on the height, and carve a habitation for yourself in the rock?
 Behold, the LORD will hurl you away violently, O you strong man. He will seize firm hold on you,
 and whirl you round and round, and throw you like a ball into a wide land; there you shall die, and there shall be your splendid chariots, you shame of your master”s house.
 I will thrust you from your office, and you will be cast down from your station.
 In that day I will call my servant Eli”akim the son of Hilki”ah,
 and I will clothe him with your robe, and will bind your girdle on him, and will commit your authority to his hand; and he shall be a father to the inhabitants of Jerusalem and to the house of Judah.
 And I will place on his shoulder the key of the house of David; he shall open, and none shall shut; and he shall shut, and none shall open.
 And I will fasten him like a peg in a sure place, and he will become a throne of honor to his father”s house.
In verse 15, the steward is “over the household.” This is not merely descriptive, but actually points to the role of the prime minister. For example, in Genesis 41:41, Joseph is put over the house of Egypt. In Numbers 12:7, Moses has been entrusted the “house” of God as his “prime minister.” In 2 Kings 15:5, Jotham is “over the household” of the King who has leprosy and is forced to leave.
Similarly, Peter is put “over the house” of the Church that Christ the King is building. This calls to mind Luke 12:42 and following, where Our Lord asks, “Who is the wise steward that the master puts ”over the household?’2012-04-24 18:35:20′”
In verse 19, we clearly see that this authority goes with the office, as Eliakim replaces Shebna.
In verse 21, we read that the prime minister is to be a father to the people; a Papa or Pope in Italian. That”s why we call his successor the Holy Father. The Papa will have the key of the House of David.
In verse 22, the words “open and shut” may sound a bit odd until we realize the connection with binding and loosing in Matthew 16:19. We will look more closely at that particular issue in the next installment.
Finally, in Isaiah 22:23, we read that the prime minister is like a “peg in a sure place,” which holds up the entire dwelling. That”s why the Church considers the Pope to be the visible source and sign of unity in the Church (see Catechism, no. 882).