Philippians 2:10-11 ESV
Letters to the Seven Churches in Asia Minor
Jesus told John to write letters to the seven churces in Asia Minor, modern day Turkey, of the things are now, and those things to take place afterwards. The book of Revelation was written around 90 A.D., while the Apostle was exiled on the island of Patmos, in the Aegean Sea, by the Romans. Christ's edit letters to the seven churches is the first of four sevenfold series in the Apocalypse, letters to the seven churches, followed by seven seals, seven trumpets and then seven bowls.
Each church is located in one of seven cities, Ephesus, Smyrna, Sardis, Thyatira, Pergamum, Philadelphia and Laodicea.
Every letter was an edict from Jesus Crist, following the same pattern.
First a differing description of Jesus; second, an "I know" declaration which introduces the diagnosis of each church's condition, both positive, except for Sardis and Laodicea, and negative, expept for Smyrna and Philadelphia; third, comfort and commands follow each diagnosis; fourth, all churches are commanded to hear and heed the letters; fifth, a blessing is promised to the one who conquers, a foreshadowing the final visions in Revelation 21-22.