The name Thyatira means continual , or perpetual, sacrifice - it was a lax and permissive church.
This small town was famous in those days for its trade guilds, and its purple cloth made of wool, and a purple colouring obtained from molluscs (Acts 16:14). It is called Akhisar today.
The Lord Jesus identifies himself as the Son of God (in 1:13 he was seen to be like the Son of Man), in his divine nature bringing judgment: a flame of fire (his eyes) to test, and feet like fine brass to trample (19:11-15, Daniel 10:6, also Hebrews 10:26-31).
Knowing the church, he commends its love, service, faith, patience and increased activity.
On the other hand, the church is severely reprimanded for permitting a woman, Jezebel, who calls herself a prophetess, to teach (I Timothy 2:12), and to entice the Lord's servants to indulge in sexual immorality (I Corinthians 5:1-5) and idolatry: she was encouraging them to consort with the world around them and to take part in their immoral practices and religion. She was given time to repent, but as she did not, she will be severely punished with all those who are seduced by her, and her children will be killed (I Corinthians 11:30, I John 5:16). In this way all churches will know that Christ searches the minds and hearts (eyes of fire), and that he will repay each one according to his deed (feet like fine brass).
The rest of the members of the church of Thyatira, who have not followed Jezebel, must preserve that which they have (the sound apostolic doctrine - Acts 15:28,29) until Christ comes again.
The church at Thyatira is a type of the general situation of the churches from the year AD 606 to 1500 AD. In this year pope Boniface III was crowned "universal bishop", beginning the medieval age. Before that, churches were autonomous, but the majority were persuaded to become "catholic", uniting in groups under the umbrella and authority of a "metropolitan" bishop, who allied himself to the local temporal leader, usually a king or prince, communicated with the other "catholic" bishops, and took part in church councils to decide on religious and administrative matters. The bishops of Alexandria, Antioch, Constantinople, Jerusalem and Rome were regarded as being the most important. With the "crowning" of Boniface III, who gave himself, among others, the title of "vicar of Christ" and "heir of St. Peter", he was given imperial authority to absorb all other bishoprics to within his own system, already very corrupt, immoral and idolatrous (the emperor had hitherto been the supreme authority of the "catholic" churches). This he and his successors would strive to do, by force of arms where there was resistance, by torture, and by inflicting death where there was no submission: the inquisition and the crusades belonged to this period. The metropolitan bishop of Constantinople escaped because Roman emperors moved over there to escape the barbarian invasions of Rome, and he gave origin to the orthodox church, which took under its wing churches in the east of Europe. Unfortunately, with the secular power it received, it also became as corrupt as the Roman Catholic Institution.
Jezebel (I Kings 16-21, II Kings 9) is a very appropriate picture of what the R.C.I. evolved into during the period we call the Dark Ages. It introduced a paganism that resulted in idolatry and spiritual fornication, and it became a new religious system bearing little resemblance to the apostolic churches, introducing doctrines such as: justification by works, baptismal regeneration, worship of angels, dead "saints" and images, celibacy for the clergy, confessionals, purgatory, transubstantiation, indulgences, penance, mariolatry, pagan ritualism, sign of the cross, holy water and holy oil, rosary, etc. In verse 22 she is to be cast into great tribulation. This means that, unlike the true church, the R.C.I. will not escape the Great Tribulation: details are given in chapter 17. Its adherents, like the children of Jezebel, will suffer physical violence and death as part of God's judgment on Jezebel.
There was a remainder, however: many other churches resisted the R.C.I. and maintained the sound doctrine undergoing terrible persecution and martyrdom promoted by the popes, much of it through the Dominican order which was in charge of the Inquisition.
Finally, we have a word to he who overcomes (I John 5:5): he who perseveres in the works of Christ, although bereft of power and authority on earth, will one day have authority, with Christ and his other saints, over the nations (20:4); he will also receive the morning star, a figure of Christ himself (22:16), indicating he can count on His presence with him always.
18 "And to the angel of the church in Thyatira write, 'These things says the Son of God, who has eyes like a flame of fire, and His feet like fine brass:
19 "I know your works, love, service, faith, and your patience; and as for your works, the last are more than the first.
20 "Nevertheless I have a few things against you, because you allow that woman Jezebel, who calls herself a prophetess, to teach and seduce My servants to commit sexual immorality and eat things sacrificed to idols.
21 "And I gave her time to repent of her sexual immorality, and she did not repent.
22 "Indeed I will cast her into a sickbed, and those who commit adultery with her into great tribulation, unless they repent of their deeds.
23 "I will kill her children with death, and all the churches shall know that I am He who searches the minds and hearts. And I will give to each one of you according to your works.
24 "Now to you I say, and to the rest in Thyatira, as many as do not have this doctrine, who have not known the depths of Satan, as they say, I will put on you no other burden.
25 "But hold fast what you have till I come.
26 "And he who overcomes, and keeps My works until the end, to him I will give power over the nations
27 'He shall rule them with a rod of iron; They shall be dashed to pieces like the potter's vessels'-- as I also have received from My Father;
28 "and I will give him the morning star.
29 "He who has an ear, let him hear what the Spirit says to the churches." '
Rev 2:18-29 (NKJV)