Revelation 3:7

Philadelphia] 28 m. SE. from Sardis, a rather rich and powerful city. 'It had the most glorious history of all the cities of Asia Minor in the long struggles against the Turks' (Ramsay). It is still to a large extent Christian.

Key of David] a reference to Isaiah 22:22. As authority over the royal house was conferred upon Eliakim, so Christ has authority in the Church, above all earthly ministers, and it is really He who admits or excludes, who gives the 'open door' of Revelation 3:8.: cp. John 10:9; John 14:6.