What does Revelation 2:15 mean?

In addition to falling into the sins of Balaam (Revelation 2:14), some members of the church at Pergamum adhered to the teaching of the Nicolaitans. The church at Ephesus hated the works of the Nicolaitans (Revelation 2:6), but some in the church at Pergamum followed the Nicolaitans' teachings.

Although Scripture does not specifically say what the Nicolaitans believed, some interpreters hazard a guess based on the construction of their name. The word for "ruler" and the word for "people" comprise the name "Nicolaitans." The Nicolaitans might have advanced the teaching that the clergy should rule the people in the churches. This strongly contradicts the biblical role of the pastor. A pastor is supposed to be a shepherd who follows the example of the Chief Shepherd, the Lord Jesus (1 Peter 5:4). Jesus, the good shepherd, loves the sheep, leads them rather than drives them, cares for them, and feeds them. When Jesus walked with Peter after the resurrection, He told Peter to feed His sheep and tend to them (John 21:15–17). In 1 Peter 5:3 Peter instructs the elders not to domineer over those in their charge. Clearly, the rule of the clergy over the laity dishonors the Scriptures.

Alternatively, the Nicolaitans may have been a sect started by an apostate, Nicolaus, who taught a doctrine of lawlessness. In this case, that meant being bound by no moral restrictions at all, including those against sexual sins or idolatry.