Nicolaitanes - The church at Ephesus (Rev. 2:6) is commended for hating the "deeds" of the Nicolaitanes, and the church of Pergamos is blamed for having them who hold their "doctrines" (15). They were seemingly a class of professing Christians, who sought to introduce into the church a false freedom or licentiousness, thus abusing Paul's doctrine of grace (comp. 2 Pet. 2:15, 16, 19), and were probably identical with those who held the doctrine of Baalam (q.v.), Rev. 2:14.
From Easton's Bible Dictionary (1897)
Note: This is an article from the public domain Easton's Bible Dictionary, originally published in 1897. This article is written from a nineteenth century Christian viewpoint, and may not reflect modern opinions or recent discoveries in Biblical scholarship. Please help the Wikipedia by bringing this article up to date.
