What the Bible says about
(From Forerunner Commentary)
Pergamos means "thoroughly married," like in a binding relationship. However, the context of these verses shows that they are in a relationship with a system—the wrong one! The doctrines of Balaam are in their congregation, as well as the doctrines of the Nicolaitans. Thus, He tells them to repent because some there, unlike Smyrna, had drifted away from what they had previously learned. They had not been faithful in the relationship to Him, even though they gave lip service to the doctrines.
John W. Ritenbaugh
What Is the Work of God Now? (Part Four)