“And to the angel of the church in Philadelphia write; These things saith he that is holy, he that is true, he that hath the key of David, he that openeth, and no man shutteth; and shutteth, and no man openeth;”
King James Version (KJV)
3:7 The holy one, the true one - Two great and glorious names He that hath the key of David - A master of a family, or a prince, has one or more keys, wherewith he can open and shut all the doors of his house or palace. So had David a key, a token of right and sovereignty, which was afterward adjudged to Eliakim, #Isaiah 22:22|. Much more has Christ, the Son of David, the key of the spiritual city of David, the New Jerusalem; the supreme right, power, and authority, as in his own house. He openeth this to all that overcome, and none shutteth: he shutteth it against all the fearful, and none openeth. Likewise when he openeth a door on earth for his works or his servants, none can shut; and when he shutteth against whatever would hurt or defile, none can open.
Re 3:7 THE CHURCH AT PHILADELPHIA The church in Philadelphia. This city was in the interior, southeast of Sardis, and had never attained the eminence of most of the other seats of the Seven Churches. That the church itself was poor and wanting in worldly endowments seems to be indicated by Re 3:8. Yet this church and that of Smyrna alone escape censure. Philadelphia is yet a city of 18,000 inhabitants, though bearing a Turkish name, has five churches and a Christian population of about 3,000. He that hath the key of David. See PNT "Re 1:18". The key of the kingdom of God as the Son of David. Hence he only opens and shuts, or determines who shall enter in, or be shut out.