I just read a book called Feeding Demons by Perry Stone. (It is available on his website.) It expounds on the lies and limitations of demons in people. It is a very good book. There are some principles worth sharing about it (but I encourage those seeking more detail to get the book and read it- I am not affiliated with him other than being a sister in Christ.)
Principle 1: God and Satan are in no way, shape or form equal forces. God is infinitely more powerful and Jesus already won the final victory over all satanic forces and demons. Satan is a defeated enemy and he knows it but lies, lies, lies.
2. Jesus has complete authority over demons. As such, those who are humbly close to Jesus also have authority over demons because of Jesus and only in His name.
3. Every person has free will to allow or not allow demons in. We cannot cast a demon out against someone’s will. They must want freedom.
4. Prayer and fasting to and for God builds up spiritual power. You get stronger against the enemy by prayer and fasting. Closeness to God is everything.
5. Jesus’ protection is available to anyone who humbly asks Him to cover and save them and has faith. Faith is crucial and allows Jesus to work through you and salvation is our hope and peace. ❤