Isaiah 22 mentions the “keys” as representing authority from a King.
Although there are parallels between Isaiah 22 and Matthew 16 there are also divergences. Isaiah’s prophecy to Eliakim has two elements; the keys to the house of David and the power to make final decisions. In Matthew, Christ’s promise to Peter has two elements as well; the keys to the kingdom of heaven and the power to forgive sins.
The first elements are similar for sure but when we look at the second that is when we see a divergence. What Jesus gave to saint Peter was not administrative but priestly, the power to forgive sins. I know there have been threads on this particular subject, the difference between the Septuagint text and the Hebrew Masoretic, but in the Septuagint there is no mention of the keys in Isaiah 22:22, “I will give him the glory of David, and he shall rule, and no one will oppose him.” (I am no Biblical scholar so I admit that I am not one who knows Greek and Hebrew and how they are translated).
The fulfillment of Isaiah 22 is seen in the Book of Revelation 3:7. Isaiah 22:22 again reads, “And I will place on his shoulder
the key of the house of David; and
he shall shut, and non shall open” (RSV-CE). Revelation 3:7 reads, “And to the angel of the church in Philadelphia write: 'The words of the holy one, the true one, who has the
key of David, who opens and no one shall shut,
who shuts and no one opens.” (RSV-CE). There are similarities to Matthew 16 and Isaiah 22, but a much closer fit can be found between Isaiah 22 and Revelation 3:7 where both elements parallel each other.
In Isaiah the keys are a symbol of authority along with the language of “shutting and opening.” We see in Revelation chapter 3 that Jesus, who says that He holds the “key of David” He is showing he is the Messiah and is the one with supreme authority. We see the power of the keys in verse 8, "I know your works. Behold, I have set before you an
open door, which no one is able to shut . . . "
Jesus gave the keys to the Kingdom to Peter. Peter was the first office holder.
Jesus notes in Matthew 16:19 that the keys come with the power to bind and loose and this is given to all the apostles, not just saint Peter. Here is what saint John Chrysostom says about this, “The authority to
bind and
loose sins is given to the apostles and transmitted to the bishops and presbyters they ordained. This authority is given for the sake of the salvation of the sinner. The sinner, ‘seeing that he is not only cast out of the Church, but that the bond of his sin will remain in Heaven, he may turn and become gentle.’”
ZP