Jesus told the church at Pergamos to repent (Revelation 2:16). That is, repent of believing and perhaps acting on the belief that they needed to join pagans in worship in order to gain them for Christ. Such a practice would end their persecution, but it would take away their witness. How could they testify of what it means to have Jesus as Lord, if they acted as though the pagan gods were lords as well? Mere doctrine saves no one. Jesus, not a better argument, saves people from their sins.
Additionally, the church needed to repent of the idea that some believers cared more for the church than Jesus did. Legalism and legalist leaders, in effect, conclude that Jesus isn’t enough to save his people from sinful behavior. If the Law is needed to show folks how to live, then Jesus becomes unnecessary. If Jesus is unnecessary, then God is unrighteous to have sent him into a cruel world to die so ignominiously on the cross. The Law condemns, but Jesus saves. The Law kills, but Jesus gives life. It is simply illogical to believe the Law is able to do what Jesus claims he alone can do. To believe otherwise, in effect, rejects Jesus as one’s Messiah.
Often the work of the Lord isn’t readily seen, because he desires to save all men (1Timothy 2:4). The church has been given authority to preach Christ to the nations (Matthew 28:18-20). If we have been given this authority, it stands to reason that we have been given authority to “root out, and to pull down, and to destroy, and to throw down, to build, and to plant” (Jeremiah 1:10), not in the sense of making war as the nations do, but, instead, we need to be strong in Christ, in order that our Gospel might pull down the strongholds of their minds, and all else that exalts itself above the knowledge of God (2Corinthians 10:5-6). This isn’t done by looking at the outward appearance of things in this world (2Corinthians 10:7). It isn’t done by becoming like the world, i.e. doing what they do but in a “Christianized” manner (doctrine of Balaam). Nor is it done by forbidding contact with unbelievers as though their touch would make us unclean (doctrine of the Nicolaitans).
If Jesus is the Messiah, then it behooves his people to preserve their witness in him and permit the Power of God in earthen vessels (2Corinthians 4:6-7) to shine out of darkness to give the light of the knowledge of God – even the light of Christ – to an ignorant, dead in their spirits, world. Preserving our witness invites persecution, and the persecuted often find themselves in trouble on every side, yet they are at peace. They may be bewildered, yet they are able to hope. They may even be physically abused, yet they know they are not abandoned. They may be humiliated by their enemies, yet they are not destroyed. In all these things persecuted believers bear to the world the death of the Lord Jesus in their bodies, that his life (i.e. the image of God – Hebrews 1:3) might also be made manifest to those who do such things (2Corinthians 4:8-10) .
Jesus said, if the church didn’t repent, he would come and fight against those leading his people astray. At first this seems to conclude Jesus wouldn’t fight against believers who had embraced the doctrines of Balaam or the Nicolaitans. Nevertheless, the Scriptures elsewhere show differently. If being obedient to the doctrines of men (doctrine of Balaam and the doctrine of the Nicolaitans) offers only lip-service to God (cp. Matthew 15:1, 8-9), and, since those who teach such things are able to keep their disciples out of the Kingdom of God (Matthew 23:13; Luke 11:52), then believers of such doctrines will suffer the same consequences of their teachers, whom they have chosen over the Lord (Luke 16:13).
Unrepentance will be dealt with through the word of God, which is the sharp sword of Jesus’ mouth (Revelation 2:16). The sword is what the Lord was ready to use against Balaam (Numbers 22:23), but this sword isn’t a carnal weapon (cp. 2Corinthians 10:4). Rather it is the spirit of the word of God (Ephesians 6:17), and it is powerful to destroy the wicked (2Thessalonians 2:8), which is what Jesus promised to do in due time.