The last Western Church Father was Isidore of Seville, who finished the Etymologies, in the year 636 AD. In Book VIII titled "The Church and sects (De ecclesia et secta)" he wrote, "The Nicolaites (Nicolaita) are so called from Nicolaus, deacon of the church of Jerusalem, who, along with Stephen and the others, was ordained by Peter. He abandoned his wife because of her beauty, so that whoever wanted to might enjoy her; the practice turned into debauchery, with partners being exchanged in turn. Jesus condemns them in the Apocalypse, saying (2:6): "But this thou hast, that thou hates the deeds of the Nicolaites." - Wikipedia
Sprirtual Understanding had not come to many in the Early Church as to what a Christian is and how the Law fits into Christianity.
The Apostle Paul received that Revelation directly from Christ Jesus. However, his preaching and writing on Grace Through Faith did not reach everyone instantaneously.
So, while he was receiving the Revelation, preaching the Revelation and convincing the Church fathers of the Revelation, Error cropped up in the Minds of zealous Believers in Christ.
Such was the case with Nicolaus (giving him the benefit of the doubt).
Paul explains how the Perfect Law Of Liberty works in the following passage.
All things are lawful unto me, but all things are not expedient: all things are lawful for me, but I Will not be brought under the Power of any. -
There are two key points in this passage:
1. In Christ we have Freedom and Liberty to do anything
2. But Bondage occurs when Liberty is abused
Licentiousness is a counter-indication of having been Born Again.