Although the Apostle John resided in Ephesus for many years (and likely died there), it was Paul who started the church within it (see Acts 19). He first visited the city, for a brief period, during his second missionary journey. During his third missionary journey he resides in Ephesus for almost three and one half years.
It is unclear who started the Christian church in Smyrna. Church tradition states that Polycarp, who is believed to have been a disciple of the Apostle John, died in the city as a martyr around 156 A.D. It is also unknown how the Christian church started in Pergamos, Thyatira, Sardis, Philadelphia and Laodicea. Although the Apostle Paul references Laodicea at least four times in his epistle to the Colossians (Colossians 2:1, 4:13 - 16), there is no record of him actually visiting the city.
Christians might have first appeared in these cities after receiving the gospel from the many people who spread it after the church began on the day of Pentecost (see Acts 8:1, 4, 11:19 - 21).
God's criticism of his people in Laodicea, the last of Revelation's seven churches, is a little hard to grasp without some background information. In assessing their standing before him, he states the following.
I know your works, that you are neither cold nor hot; I would that you be either cold or hot. So then, because you are lukewarm, and are neither cold nor hot, I will spew you out of My mouth (Revelation 3:15 - 16, HBFV)
Laodicea, because it lacked its own water supply, had to have it transported from the nearby city of Hierapolis. The water in Hierapolis came out of the ground hot. After its journey of six miles (9.6 kilometers) to Laodicea, however, the water became lukewarm. Although cold water was desired for drinking purposes and hot water for bathing, lukewarm water was good for neither. Citizens had to make the water either hot or cold in order for it to be of use to them.
God is drawing the analogy that, like the Laodiceans and their water, he prefers dealing with people who are either hot (zealous for him and do many good works) or cold (not converted). He does not like those who are converted but live their lives with only a half-hearted zeal toward him.
Hierapolis, a town in the Lycus River Valley, was located in the Roman province of Asia roughly 6 miles (9.6 kilometers) north of Laodicea. The town was founded on hot springs that served as a thermal spa, which made the destination popular with ancient Romans. The city was destroyed by an earthquake that occurred during the latter part of Nero's reign.
Hierapolis is mentioned only once in the New Testament (Colossians 4:13). It is referenced as a place (along with Laodicea) where Epaphras, one of Paul's fellow evangelists, was looking out for their spiritual well-being. The church in the city, as well as the one in Laodicea, was likely started by Epaphras.
Tradition states that Philip, one of Jesus' original twelve apostles, eventually settled in the western Asia Minor city of Hierapolis and suffered martyrdom in it (Foxe's Book of Martyrs). The other Philip mentioned in the New Testament, Philip the Evangelist (Acts 6:1 - 7), who had four virgin daughters (21:8 - 10), is also believed to have taken himself and his family to live in Hierapolis (The Book of Acts in Its Palestinian Setting by Richard Bauckham, Chapter 3).