The Bible mentions demons fifty-seven times. If you believe in the Bible, you must also believe in the reality of demons in the world.
Demons are negative spiritual entities.
They hate human beings, and they try to harm us in many ways. Demons try to control, harass, torment us, or drive us to do things we ought not to do or wish we didn't do. Temper, depression, fear, sickness, to mention a few, are demons. The positve power of our Lord Jesus Christ is infinitely greater than the limited negative power of demons. So through Him, and Him alone, we can triumph totally over all demons.