Revelation opens with a message to seven churches. The fourth church, the one in the center, is Thyatira. Thyatira's position in the seven indicates that God's message to her is heart and soul of his message to all the churches.
The passage is a metaphor that points back to Israel's ancient history. Jezebel, the wife of Ahab, seventh king of Israel, was notoriously wicked. She was not a Jew. She grew up a worshipper of Baal. She embodied several profound corruptions.
First, she overthrew God's creation order. She dominated her husband, Ahab. She was the first feminist in biblical history.
Second, she introduced Israel to Baal worship. The adherents of Baal worshiped with sexual immorality. They worshiped with ritual cult prostitution in temples consecrated to Baal. He also encouraged sexual perversion. Baal encouraged sex role confusion. Males acted feminine and females masculine. Baal worship also involved infanticide, the offering of infants as living sacrifices.
Western culture looks like ancient Israel during the days of Jezebel. The same deceiving spirits have reappeared in more sophisticated, modern guise. With Satan's "deep secrets" he is destroying first the family, then the church, and last the culture that leans on the church for strength and stability. The legitimization of homosexuality, the abuses of feminism, the divorce culture, transgender confusion, and the promotion of abortion all point to the sins of Jezebel and the god she worshiped, what Revelation calls the "deep secrets of Satan."
How should we respond? With repentance. God judged Jezebel with violence. In fulfillment of prophecy she was thrown from an upper story window and eaten by dogs. All of her descendants were put to the sword. This should motivate us to repent of our sins, the sins of our fathers, and the sins of our culture. Turn from the "deep secrets of Satan," recognize their destructive nature, and put your hope in the living God.