The only information from the NT that we have regarding the Nicolaitan movement is found here in Revelation 2:6 and 2:15. Irenaeus linked this movement with Nicolaus, who was one of the seven deacons in Acts 6:5 (Against Heresies 1.26.3). But we agree with Hemer that this view is highly “doubtful.” In fact, Clement of Alexandria argued that Irenaeus’s view was false (Stromata 2.20). Eusebius states that this sect only existed for “a very short time” (Church History 3.29.1). Irenaeus’ information might’ve been simply speculated from the text of Revelation 2, and nothing seems to have been gathered from historical sources—written or otherwise. Indeed, Mounce writes, “It may be that the only information the patristic writers had was the book of Revelation itself.”
Osbourne infers that this could be a Gnostic false teaching, because of the mention of Balaam in verse 14. This is also mentioned in 2 Peter 2:15 and Jude 11, which is linked to a Gnostic, licentious false teaching. He also argues that the language of the “deep things of Satan” could likewise be Gnostic language (Rev. 2:24). While the teachings of the Nicolaitans are unclear, their practices are crystal clear. The text tells us that their primary sin were idolatry (v.14) and sexual immorality (Rev. 2:20-21; porneia).
 Colin J. Hemer, The Letters to the Seven Churches of Asia in their Local Setting (England: Sheffield Academic Press, 1989), 88.
 Robert H. Mounce, The Book of Revelation, The New International Commentary on the New Testament (Grand Rapids, MI: Wm. B. Eerdmans Publishing Co., 1997), 71.
 Grant R. Osborne, Revelation, Baker Exegetical Commentary on the New Testament (Grand Rapids, MI: Baker Academic, 2002), 120.