The authtor of the paper „Is there a devil?“ gives teaching about fallen spirits and their working in the world. They are shoun truths dearly contained in biblical books and thoughtful theology which are taught by the Magistry of Church. The paper does not demand full explanation of demondogy. It only wants to say that theology would always be incomplete and uncomprehensible while it does not start to throw light on the world of angels. Christology ignoring satan is incorrect and can never understand the range of salvation.