What does the Bible actually say about demons?
For most of my life, I've attended and worked for an event that tends to lean to the more legalistic side concerning entertainment, and stuff like Harry Potter in particular. I've also heard stories from these people about encounters they'd had with demons, and I've heard so many of these stories that it seems really common to me. Now, I go to bed every night and sometimes I can barely fall asleep becasue I keep thinking I'll turn around and see a demon standing in my room because I read a book with magic or spirits in it, or because I have a Harry Potter Lego set in my closet, or something like that, because I've "let them in" and given the devil a foothold. The basic mentality of what I've been taught is "if you feel a dark feeling, it means there's a demon nearby and you need to wash something with the blood of Jesus...." I don't want to be ruled by my emotions like this, because I've learned that my emotions cannot be trusted. Rather, I want some good, solid, teaching on what the Bible says about the spiritual world, and whether we need to worry about it or not. On the other hand, I trust that these people are not lying, and they've really seen this stuff, which really scares me. By the way, I would never use a ouiji board or any kind of instument like that, but entertainment is kind of a grey area...
Thanks for your question. The information below from carm.org may help on understanding a bit more about Jesus.
I can't say whether what those people told you is true or not, but we have to be very careful listening to others, and as you say, we need to instead listen to the Bible. And from the Bible we know that God absolutely has all power over all evil spirits. As a Christian, you have the Holy Spirit inside you, and so it would be impossible for a demon to inhabit the same space as God. Also, Jesus demonstrates his power over demons in the Bible, and so if you are worried or scared, pray and ask His help to give you courage. But know that demons have no power over you, and are afraid of the name of Jesus. Again, if you are trusting in Jesus, you have nothing to be afraid of.
Demons are evil spirits that are opposed to God and God's people. They appear to be fallen angels: 2 Pet. 2:4 & Jude 6 are primarily referenced in the New Testament.
Matt. 4:24, "And the news about Him went out into all Syria; and they brought to Him all who were ill, taken with various diseases and pains, demoniacs, epileptics, paralytics; and He healed them."
Matt. 8:28, "And when He had come to the other side into the country of the Gadarenes, two men who were demon-possessed met Him as they were coming out of the tombs; they were so exceedingly violent that no one could pass by that road."
Mark 3:22, "And the scribes who came down from Jerusalem were saying, 'He is possessed by Beelzebul,' and "He casts out the demons by the ruler of the demons."
Luke 4:35, "And Jesus rebuked him, saying, "Be quiet and come out of him!" And when the demon had thrown him down in their midst, he came out of him without doing him any harm."
John 8:48-49, "The Jews answered and said to Him, "Do we not say rightly that You are a Samaritan and have a demon?" 49 Jesus answered, "I do not have a demon; but I honor My Father, and you dishonor Me"
Demons are spiritual beings without physical form. They are evil spirits that are opposed to God and his work. They were probably created before the world was and, like Satan, fell away from God. Some believe that Rev. 12:4 is a reference to a third of the angels falling and becoming demons.
The term demon comes from the Greek "daimon." Demons are found in the New Testament as being able to possess people (Matt. 8:28-34; Mark 5:1-4) and animals (Matt. 8:32). They are very strong (Mark 5:4). They are also called unclean spirits (Luke 8:29), seem to have a heirarchy of rulership in their demonic realm (Matt. 12:24-27), and can have sacrifices offered to them (1 Cor. 10:20). Also, they will be judged in the future (Matt. 8:29). They cannot be redeemed.
Paul recognized demonic forces and referred to them as principalities (Rom. 8:38) and said that we struggle against them (Eph. 6:11-12). He speaks of them in the heavenly places, but this does not mean heaven where God is but the upper area above the earth.
Jesus was able to cast out demons from the demon-possessed people (Matt. 8:32) and was accused of being demon-possessed (John 7:20; 8:48).