NICOLAUS nĭk’ ə lā’ əs (Νικόλαος, G3775, conqueror of the people), the proselyte of Antioch chosen as one of the seven men to serve the church in Jerusalem (Acts 6:5). The reference to a proselyte meant that he was a Gentile who had become a convert to Judaism, and subsequently to Christianity. Because his name was Gr., as well as the others among the seven men chosen to distribute the food in the dole practiced by the Jerusalem church, it has been supposed that the others were proselytes also. It seems rather that they were all Gentiles, and the designation “proselyte” applied only to Nicolaus meant that he alone had come to Christianity through Judaism, the other six having come directly from paganism, or at least not having been converted to Judaism. This, of course, raises the entire question of circumcision and its importance in the Early Church. Because of a due consideration for the importance of such Jewish practices even in the Early Church, it has been most often assumed that all seven were either proselytes or Jews using Gr. names.
Nicolaus was thought by the Church Fathers to have been the founder of the heretical sect known as the Nicolaitans (Rev 2:6, 15). Irenaeus excused him from responsibility for this by indicating that it was a misunderstanding of his teaching that had produced the Nicolaitans. Nicolaus, according to Irenaeus, had taught that “the flesh must be abused.” By this he had meant that the body must be buffeted to be kept under control. The Nicolaitans changed his teaching to mean that the flesh could be treated in any fashion, that the flesh was insignificant and of no concern. Thus a man could live in any fashion that he wished; all of which led to shameless immorality. On the basis of this teaching the followers of Nicolaus practiced all kinds of wickedness.
International Standard Bible Encyclopedia (1915)
(English Versions of the Bible), nik’-o-las (Nikolaos): One of "the seven" chosen to have the oversight of "the daily ministration" to the poor of the church in Jerusalem (Ac 6:5). He is called "a proselyte of Antioch"; the other 6 were therefore probably Jews by birth. This is the first recorded case of the admission of a proselyte into office in the Christian church. Some of the church Fathers (Irenaeus, Hippolytus, Pseudo-Tertullian) state that he was the founder of the sect called NICOLAITANS (which see) (Re 2:15). Other Fathers seem to suggest that this was a vain claim made by this sect in seeking apostolic authority for their opinions. It may be that the opinions of this sect were an antinomian exaggeration of the preaching of Nicolaus.