Colossians 2:1 ESV For I want you to know how great a struggle I have for you and for those at Laodicea and for all who have not seen me face to face,
Colossians 4:13-16 ESV For I bear him witness that he has worked hard for you and for those in Laodicea and in Hierapolis. (14) Luke the beloved physician greets you, as does Demas. (15) Give my greetings to the brothers at Laodicea, and to Nympha and the church in her house. (16) And when this letter has been read among you, have it also read in the church of the Laodiceans; and see that you also read the letter from Laodicea.
In writing to the Christians in Colossians Paul sends greetings to them through a Laodicean woman named Nympha who had a church in her house, (See 4:15). He also greeted Archippus (See 4:17) who may have also been from Laodicea.
Since Colossians was written by Paul we can assume that there was a strong Christian group in Laodicea as early as 50 AD. In Rev.3:15-16 we have the severe rebuke from our Lord Jesus Christ against the believers in Laodicea.
Revelation 3:15-16 ESV "'I know your works: you are neither cold nor hot. Would that you were either cold or hot! (16) So, because you are lukewarm, and neither hot nor cold, I will spit you out of my mouth.
The question then arises as to what is meant by our Lord when He classified the believers of Laodicea as being "lukewarm."
It is thought that the Laodiceans were being criticized for their neutrality or lack of zeal in spiritual principles, therefore, being lukewarm. Based on this understanding the term "Laodicean" is used to refer to those who are neutral or indifferent in the matters of the faith.
There is another meaning however other than being neutral or indifferent. The water supply to the city was lukewarm water. There were hot springs in nearby Hierapolis. Laodicea had an aqueduct from the hot springs of Hierapolis that carried the water five miles to the city of Laodicea. The water was lukewarm and tepid making it hard to drink. The idea is that hot water is useful and cold water is useful but lukewarm water is not and therefore spit out of the mouth.