The Key of David

Q. Is 22: 22 God talks about Eliakim as a replacement for Shebna. He said, “I will place on his shoulder the key to the house of David; what he opens no one can shut, and what he shuts no one can open.”
Jesus used the same words about the church in Philadelphia in Rev 3:7 “To the angel of the church in Philadelphia write: These are the words of Him who is holy and true, who holds the key of David. What He opens no one can shut, and what He shuts no one can open.
What is the meaning and significance of those words? What is the key to the house of David?

A. The term “key of David” appears only in the two passages you cited in the Bible. First, let’s note Is 22:22’s preceding context:
Is 22:21 And I will clothe him with your tunic And tie your sash securely about him. I will entrust him with your authority, And he will become a father to the inhabitants of Jerusalem and to the house of Judah.

The tunic and sash were symbols of authority worn by priests (Ex 28:4, 39, 40; Lev 8:7, 13; Lev 16:4), so was the key on the shoulders, which represents governing power:
Is 9:6 For a child will be born to us, a son will be given to us; And the government will rest on His shoulders; And His name will be called Wonderful Counselor, Mighty God, Eternal Father, Prince of Peace.

Eliakim was master of Hezekiah’s household, entrusted with the king’s authority, and a “father” to Judah. This is similar to Joseph:
Gen 45:8 Now, therefore, it was not you who sent me here, but God; and He has made me a father to Pharaoh and lord of all his household and ruler over all the land of Egypt.

Just as Joseph was second-in-command after Pharaoh, Eliakim had full authority after Hezekiah. In this sense he was a “type” of Christ.

Next, let’s note Rev 3:7’s subsequent context:
Rev 3:8 ‘I know your deeds. Behold, I have put before you an open door which no one can shut, because you have a little power, and have kept My word, and have not denied My name.

John used Isaiah’s imagery to convey the idea that Jesus is the Son of David who holds final authority over his house. He is the one who will sit on David’s throne forever (Lk 1:32). The key of David can, but need not be, a literal physical key.