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 (2Pe 2:15,16,19), and were probably identical with those who held the doctrine of Baalam (q.v.), Rev 2:14.
[Easton Bible Dictionary]
Lord of the people; foreigner or glutton, as interpreted by others, the son of Beor, was a man of some rank among the Midianites (Num 31:8; Num 31:16). He resided at Pethor (Deu 23:4), in Mesopotamia (Num 23:7). It is evident that though dwelling among idolaters he had some knowledge of the true God; and was held in such reputation that it was supposed that he whom he blessed was blessed, and he whom he cursed was cursed. When the Israelites were encamped on the plains of Moab, on the east of Jordan, by Jericho, Balak sent for Balaam "from Aram, out of the mountains of the east," to curse them; but by the remarkable interposition of God he was utterly unable to fulfil Balak's wish, however desirous he was to do so. The apostle Peter refers (2Pe 2:15,16) to this as an historical event. In Mic 6:5 reference also is made to the relations between Balaam and Balak. Though Balaam could not curse Israel, yet he suggested a mode by which the divine displeasure might be caused to descend upon them (In Num 25). In a battle between Israel and the Midianites (q.v.) Balaam was slain while fighting on the side of Balak (Num 31:8).
The "doctrine of Balaam" is spoken of in Rev 2:14, in allusion to the fact that it was through the teaching of Balaam that Balak learned the way by which the Israelites might be led into sin. (See NICOLAITANES.) Balaam was constrained to utter prophecies regarding the future of Israel of wonderful magnificence and beauty of expression (Num 24:5-9,17). [Easton Bible Dictionary]