Bruce Longenecker’s book, “The Lost Letters of Pergamum” (pp. 165-166) illustrates their teaching in a story about a Nicolaitan (Kalandion) that attended the Pergamum church. Kalandion is visiting a Christian who has been imprisoned for his faith.
“Kalandion had already visited him on several days in hope of deterring him from his persistent atheism. Kalandion, who is clearly concerned about his own reputation as a Christ worshiper, suggested that allegiance to Jesus Christ is not incompatible with worship of The Roman emperor and the lesser gods. Moreover, eating meat sacrificed to idols is not a religious offense. According to Kalandion, because all food comes from the most high god, and because idols have no real existence or power, Christians should not worry about eating sacrificed food. Demetrius thought that in principle, Kalandion’s argument about idol meat was correct. However, he felt that eating meat sacrificed to idols in the context of a guild banquet would signal his compliance with the imperial cult and would involve a compromise of his singular devotion to Jesus Christ.”