Philadelphia (modern Alashehir) is about 45km south east of Sardis. Its original citadel was up the hill on the north east edge of what is now Boz Dağ. Its name came from Attalus II of Pergamon. He was given the title 'Philadelphus' because of his love for his brother, Eumenes, who preceded him as king. Coins of the period had two identical heads on them. It was a prosperous city, filled with trading and pagan temple worship, and also a large synagogue of Jews. The city was on the major trade route to the seaport of Smyrna 140km to the west, and it was the gateway to the east on the ancient Persian Royal Road.

Jesus describes Himself as the holy God (John 10:30) and the truth-giver to humanity (John 12:49; 14:6). The key of David was given to Eliakim the palace administrator in Isaiah 22:22: "I will place on his shoulder the key to the house of David; what he opens no one can shut, and what he shuts no one can open." But Isaiah's text also prophesied Jesus who also had the spirit of wisdom (Isaiah 11:1-2). The key was to open the door which devout but misguided Jews could not unlock (Matthew 23:13-15); it was the door to life with God through Jesus.

When Jesus opens a door, nobody can close it; and when He locks a door, nobody can force it open. The church in Philadelphia was a missionary church and the Lord promised to open doors for the gospel. Even though they had little strength, Jesus promised to make them effective – sharing the gospel and leading people to Himself. They had been faithful in small ways, and the Lord had found them trustworthy. Now Jesus would give them greater responsibility for missionary outreach (Matthew 25:21).

Today's passage has stirred many generations of evangelists and missionaries, evangelistic churches and individuals in the workplaces. Paul also urged the believers in Colossae, 120km to the south east of Philadelphia: "Devote yourselves to prayer, being watchful and thankful. And pray for us, too, that God may open a door for our message, so that we may proclaim the mystery of Christ, for which I am in chains. Pray that I may proclaim it clearly, as I should. Be wise in the way you act towards outsiders; make the most of every opportunity. Let your conversation be always full of grace, seasoned with salt, so that you may know how to answer everyone.' (Colossians 4:2-6). The Lord Jesus opens doors for the gospel; it is our responsibility to walk through those doors with the message of salvation, and not be afraid (Romans 1:16). This church received no rebuke from Jesus. Instead they were told to refuse to be governed by their weakness; to expect Him to open doors of opportunity for them to explain about Jesus and the gospel. Ask Him to open a door, and then go through it with Christ's message of salvation.