The Lord Jesus' letter to the church at Thyatira is the longest among the seven recorded in Revelation. Although they were faithful in their works to the city, had a strong charity among themselves, and were evidently growing in their reputation and perhaps even in number, the Lord Jesus used some very harsh language to rebuke their behavior.
Whether or not the woman who held influence in the church was actually named Jezebel, she had entrenched herself as a prophetess. Her namesake in the Old Testament (1 Kings) was the wicked queen and wife of King Ahab of Israel during the days of Elijah. Her evil deeds are recorded throughout seven chapters--more than any other woman in Israel's history!
The Jezebel of Thyatira had been allowed "to teach and to seduce my servants to commit fornication, and to eat things sacrificed unto idols" (Revelation 2:20). It is not clear if the Lord spoke of physical fornication among the church members, but the practice of sacrificing to idols was a serious rebellion against the second commandment and a clear violation of God's Word (Exodus 20:4-5).
Those who were committing "adultery with her" (Revelation 2:22) had entered into "the depths of Satan" (Revelation 2:24). Whether this behavior was a physical practice or not (as was common among the pagan religions of the day), it is most certainly identified as spiritual adultery when those who name the name of Christ worship other gods (Jeremiah 3:1, 20: Hosea 9:1, etc.). May God protect us from such horrible leadership. HMM III