The Nicolaitanes are the followers of that Nicolas who was one of the seven first ordained to the diaconate by the apostles. They lead lives of unrestrained indulgence. The character of these men is very plainly pointed out in the Apocalypse of John, [when they are represented] as teaching that it is a matter of indifference to practice adultery, and to eat things sacrificed to idols. Wherefore the Word has also spoken of them thus: “But this you have, that you hate the deeds of the Nicolaitanes, which I also hate.”
John, the disciple of the Lord, preaches this faith, and seeks, by the proclamation of the Gospel, to remove that error which by Cerinthus had been disseminated among men, and a long time previously by those termed Nicolaitans, who are an offset of that “knowledge” falsely so called, that he might confound them, and persuade them that there is but one God, who made all things by His Word.- ibid
Clement of Alexandria
Such also are those who say that they follow Nicolaus, quoting an adage of the man, which they pervert, “that the flesh must be abused.”… But they, abandoning themselves to pleasure like goats, as if insulting the body, lead a life of self-indulgence; not knowing that the body is wasted, being by nature subject to dissolution; while their soul is buffed in the mire of vice; following as they do the teaching of pleasure itself, not of the apostolic man.
Nicolaus, they say, had a lovely wife. When after the Savior’s ascension he was accused before the apostles of jealousy, he brought his wife into the concourse and allowed anyone who so desired to marry her. For, they say, this action was appropriate to the saying: “One must abuse the flesh.” Those who share his heresy follow both his action and his words simply and without qualification by indulging in the gravest enormity. – ibid
John, however, in the Apocalypse is charged to chastise those “who eat things sacrificed to idols,” and “who commit fornication.” There are even now another sort of Nicolaitans.
We do not aim at destroying the happiness of sanctity, as do certain Nicolaitans in their maintenance of lust and luxury. – ibid
But Nicolaus has been a cause of the wide-spread combination of these wicked men. He, as one of the seven (that were chosen) for the diaconate, was appointed by the Apostles. (But Nicolaus) departed from correct doctrine, and was in the habit of inculcating indifference of both life and food. And when the disciples (of Nicolaus) continued to offer insult to the Holy Spirit, John reproved them in the Apocalypse as fornicators and eaters of things offered unto idols.