Jesus "has eyes like a flame of fire" and He's warning the church in Thyatira that He takes sexual sin very seriously. In A Letter to the Sexually Immoral, Jesus at first praises these believers: they're busy in faith, love and endurance. But this church is tolerating sexual sin, which God, in His Word and His wisdom, likens to spiritual adultery. These are the "deep things of Satan," Jesus says, very tempting in the meantime—but fruitless in the end.