Question: "What was Jesus’ message to the church in Philadelphia in Revelation?"
Answer: Revelation 3:7-13 records Christ’s message to the sixth of the seven churches addressed in Revelation 2–3. The Philadelphian church is the recipient of this letter. Philadelphia was a city in Asia Minor (modern-day Turkey) on the Imperial Post Road, an important trade route.
The message is from the Lord Jesus Christ through an angel or “messenger” (likely a reference to the pastor): “To the angel of the church in Philadelphia write . . .” (Revelation 3:7). This was not John’s personal message to these believers; it was a message from the Lord, who identifies Himself as “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.” This description of Jesus emphasizes His holiness, His sovereignty, and His authority. The reference to the key of David is an allusion to the Messianic prophecy of Isaiah 22:22. Jesus is the one who opens and shuts, and no one can say Him nay.
Jesus affirms the church’s positive actions: “I know your deeds. See, I have placed before you an open door that no one can shut. I know that you have little strength, yet you have kept my word and have not denied my name” (Revelation 3:8). The church of Philadelphia was weak in some respects, yet they had remained faithful in the face of trial. Because of this, the Lord promises them an “open door” of blessing.
Jesus’ letter then condemns the enemies of the Philadelphian believers: “I will make those who are of the synagogue of Satan, who claim to be Jews though they are not, but are liars—I will make them come and fall down at your feet and acknowledge that I have loved you” (Revelation 3:9). Those who persecuted the believers (the persecutors were religious hypocrites in this case) would one day realize Christ loves His children. The church of Philadelphia would be victorious over its enemies.
Jesus encourages the Philadelphian believers regarding His future coming: “Since you have kept my command to endure patiently, I will also keep you from the hour of trial that is going to come upon the whole world to test those who live on the earth. I am coming soon. Hold on to what you have, so that no one will take your crown” (Revelation 3:10-11). The church’s faithful endurance would serve as a blessing. Jesus would take them to be with Him before the coming tribulation (1 Thessalonians 4:13-18). He also exhorts them to remain faithful, because this would lead to rewards in the afterlife. Based on this and other passages, many Bible interpreters conclude that the rapture is an event distinct from the second coming of Christ. The fact that the Philadelphians are promised to be preserved from the time of the tribulation corresponds with the pretribulational view of the rapture.
Jesus provides a final promise to the believers in Philadelphia and to all believers: “Him who overcomes I will make a pillar in the temple of my God. Never again will he leave it. I will write on him the name of my God and the name of the city of my God, the new Jerusalem, which is coming down from out of heaven from my God; and I will also write on him my new name” (Revelation 3:12). Professor Thomas Constable notes, “God promised that He will not just honor overcomers by erecting a pillar in their name in heaven, as was the custom in Philadelphia. He will make them pillars in the spiritual temple of God, the New Jerusalem (21:22; cf. Gal. 2:9; 1 Cor. 3:16-17; 2 Cor. 6:16; Eph. 2:19-22; 1 Pet. 2:4-10).” (Source: Thomas Constable, Notes on Revelation at http://soniclight.org/constable/notes/pdf/revelation.pdf.)
So, those who struggled with weakness Jesus makes everlasting pillars in the house of God. We can do all things through Christ who strengthens us (Philippians 4:13). Jesus’ words of comfort certainly would have been a blessing to the Philadelphians who had faithfully stood for Christ in their pagan culture. His words continue to serve as an encouragement to faithful believers today.