It is most unlikely that the name “Jezebel” was the actual name of this sister in the congregation. Instead, the Lord used a name well known from the Old Testament to shock the congregation into recognizing what this sister was in fact teaching. Jezebel was the Sidonian wife of King Ahab (1 Kings 16:31), who incited her husband to serve idols (1 Kings 21:25f), especially Baal. That, at bottom, was what this lady in the church was doing. To achieve that end she “called herself a prophetess” and set about “teaching and seducing” the other members of the church in Thyatira.
20 But I have this against you, that you tolerate that woman Jezebel, who calls herself a prophetess and is teaching and seducing my servantsto practice sexual immorality and to eat food sacrificed to idols.