Sardis was a church not unlike churches today. They had brought the world into the church and corrupted the mission of the church. They were dead in many ways and even the few faithful were dying. Jesus Christ sends them and any church that follows their ways a very stark warning: repent or face judgment. This messages speaks to all churches of all time to make sure they stay on point and preach the Bible and glorify Christ alone.
Thyatira was a church that was steeped in sin. They had a female prophetess who unabashedly led the people into idolatry and sexual sin. While there were those in the church that rejected her false doctrines and lifestyle, the Elders of the church turned a blind eye to the sin. This warning from Jesus Christ goes to every church in every generation to rid sin from the church. A failure to do so will result in exacting judgment. The overcomers, however, will be rewarded beyond measure.
Pergamos was a city centered in pagan religion. The church there began to compromise with pagan beliefs which led to a stern rebuke by Jesus Christ. Today this message from Christ serves as a warning to our churches not to compromise with false teaching and sinful living. Those churches and believers who stay loyal to Christ will be rewarded greatly.