Another book I would recommend is “The Screwtape Letters” (1942) by C.S. Lewis. This is from the preface: “There are two equal and opposite errors into which our race can fall about the devils. One is to disbelieve in their existence. The other is to believe, and to feel an excessive and unhealthy interest in them.”
Let me repeat myself: We DO NOT need to fear the demons who do their work in the spirit realm! When you were saved, you were given the gift of the Holy Spirit to dwell IN YOU. Did you get a “junior” Holy Spirit? NO! You got the same Holy Spirit that was in Jesus Christ when He walked on the water and opened the eyes of the blind. If you compared the Holy Spirit in you to the power of satan: satan’s power is like a little firecracker (pop), and the power of the Holy Spirit in you is like a NUCLEAR BOMB (BOOM)!
There is just no comparison because our Father God is so much greater than a fallen angel.