What is the church according to the one who has the Key of David?

What is the church according to the one, the only, holy gatekeeper?

“This is what the holy one, the true one, the one who has the key of David, the one who opens and no one can shut, and who shuts and no one can open, says: ‘I know your works (behold, I have put before you an opened door that no one is able to shut) that you have a little strength, and have kept my word, and did not deny my name. Behold, I am causing those of the synagogue of Satan, the ones who call themselves Jews and are not, but are lying—behold, I will make them come and kneel down before your feet and acknowledge that I have loved you. Because you have kept the word of my patient endurance, I also will keep you from the hour of testing that is about to come upon the whole inhabited world, to put to the test those who live on the earth. I am coming quickly! Hold fast to what you have, so that no one may take away your crown. The one who conquers, I will make him a pillar in the temple of my God, and he will never go outside again, and I will write on him the name of my God and the name of the city of my God, the new Jerusalem that comes down from heaven from my God, and my new name. The one who has an ear, let him hear what the Spirit says to the churches.’

"On that day I will call to my servant, Eliakim son of Hilkiah,
    and I will clothe him with your tunic,
and I will bind your sash firmly about him,
    and I will put your authority into his hand,
and he shall be like a father to the inhabitants of Jerusalem
    and to the house of Judah.
And I will put the key of the house of David on his shoulder,
    and he shall open and no one will be able to shut;
    and he shall shut and no one will be able to open.
And I will drive him in like a peg into a secure place,
    and he will become like a throne of glory to the house of his father.
And they will hang all of the heaviness of his father’s house on him,
    the offspring and the offshoot,
all of the small vessels,
    from the bowls to the jars."  Isaiah 22

“Ask and it will be given to you; seek and you will find; knock and it will be opened for you. For everyone who asks receives, and the one who seeks finds, and to the one who knocks it will be opened....Enter through the narrow gate, because broad is the gate and spacious is the road that leads to destruction, and there are many who enter through it, because narrow is the gate and constricted is the road that leads to life, and there are few who find it!"  Matt 7

"Then Jesus said to them again, “Truly, truly, I say to you, I am the door of the sheep. All those who came before me are thieves and robbers, but the sheep do not listen to them. I am the door. If anyone enters through me, he will be saved, and will come in and will go out and will find pasture."  John 10