NOTES for Rev 2:24
It is already difficult for us now to understand exactly what was happening in the church of the city of Thyatira, whom exactly Jesus compares with Jezebel and why. Jezebel, who in antiquity effectively ruled the Northern, Israelite, Kingdom, was famous for deciding to introduce there a second official cult, an openly pagan cult; evidently it was the cult of the Baal of Carmel, who was worshiped on Carmel as lord of heaven.
Previously paganism, of course, had also in fact flourished in the Northern Kingdom, but formally Yahwism was preserved there, though "reformed." Jezebel threw off all masks and discarded all formalities, introducing the official state cult of a pagan deity.
It is possible that the study of the "depths of Satan" mentioned by the Savior was also spiritually akin to the situation with Jezebel and the cult she introduced. It is hard to say exactly in what sense the local "Jezebel" studied these depths and how far she immersed herself in them. The issue may be the unhealthy interest in the dark world and dark powers that Christians have often had and still have. Some of them want to know everything about hell and demons: it seems to them that such knowledge is necessary for full spiritual life or for "spiritual safety."
Sometimes people even speak of "fighting the devil," which these people supposedly conduct. In fact, however, it is not at all necessary to know everything about Satan's works in order to avoid them. For this one must know God, God's will, and God's works, in which a Christian will have to participate one way or another. And the desire to know everything about demons and hell usually only distracts from the main thing and can only complicate a person's life, sometimes quite seriously. This, strictly speaking, is what the Savior reminds John about.