Revelation 3:7: 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.

John addressed his sixth letter to the angel (servant)¹ of the church in Philadelphia, whose bishop may have been a man named Demetrius.²

Philadelphia was the city of brotherly love.³ The name of this city was derived from King Attalus Philadelphus of Pergamos, who had great affection for his brother.⁴ Philadelphia has also been called Little Athens because of its magnificent temples and public buildings.⁵ Today, the city is called Alasehir in modern Turkey.⁶ It was the last city in Asia Minor to fall under Turkish control in about 1392 AD,⁷ but it still remained predominantly Christian even after its fall.⁸

Philadelphia was located about 25 miles southeast of Sardis⁹ and was built by King Attalus in approximately 189 BC.¹⁰ It became an important inland commercial center as coastal cities declined in economic importance, and because it was on a trade route leading to Persia.¹¹

Christ did not rebuke or condemn the Philadelphian saints.¹² They had generally remained holy¹³ and true to the gospel.¹⁴ Therefore, Christ identified himself to them as holy¹⁵ and true.¹⁶ Since Christ is holy and embodies all truth,¹⁷ his promises to bless the righteous and to condemn the wicked are certain and unalterable.¹⁸

Christ's unmatched power to both bless and condemn¹⁹ is embodied in the key of David,²⁰ which only he possesses.²¹ With this key, Christ openeth, and no man shutteth; and shutteth, and no man openeth.²² Revelation 5:5 illustrates the use of this key where Christ alone has power to open the book with seven seals.²³ The key of David also includes power to open and close the postmortal spirit world²⁴ and to either admit or exclude people from the kingdom of God.²⁵

The key of David derives its meaning from two separate symbols. First, in scriptural terms a key symbolizes authority or power possessed by the key holder.²⁶ The second symbol is David,²⁷ the second king of Israel.²⁸ His name is synonymous with absolute power and dominion.²⁹ David's rule over his earthly kingdom is a type for Christ's absolute power to govern his kingdom.³⁰ Isaiah prophesied that "the increase of his government and peace there is no end, upon the throne of David."³¹ Jesus Christ was the rightful heir to hold the key of David,³² because he descended from David through both his mother Mary and Joseph, his supposed father.³³ By birth and by right, Jesus was the legal heir to David's kingdom.³⁴ With the key of David, Christ shall rule with absolute power³⁵ over all nations and people,³⁶ in all spiritual and temporal matters,³⁷ and in matters of both life and death.³⁸

Revelation 3:8: I know thy works: behold, I have set before thee an open door, and no man can shut it: for thou hast a little strength, and hast kept my word, and hast not denied my name.

The works of the Philadelphian saints were good.³⁹ Therefore, Christ uses the key of David to open to them the door leading to eternal life.⁴⁰ The Holy and True assures the Philadelphian saints that no man has power to shut or deprive them of the door Christ opened to them.⁴¹ Some scholars mistakenly interpret the open door as an opportunity to preach the gospel.⁴² But the context of this verse clearly shows that the door of heaven is open to the faithful saints.⁴³ Despite their little strength (weakness)⁴⁴ and their small number,⁴⁵ the Philadelphian saints kept the word of God⁴⁶ and did not deny Christ to save themselves from persecution.⁴⁷