As we look at our identity as The Children of God it’s really important to understand our authority and to be able to exercise it. Sharon Gakin wrote a great article explaining her experience exercising her spiritual authority over demons (see below). 
Jesus encountered demons, and so will we. They are active all over the world, but we don’t have to fear them; Jesus gave us authority over them: Mark 16:17 "And these signs will accompany those who believe: in my name they will cast out demons; they will speak in new tongues;
But we must each have our own authority from Christ. Acts 19 tells the story of the Sons of Sceva who tried to cast out demons “in the name of Jesus whom Paul teaches about”. That didn’t turn out very well for them. We are saved directly by Christ, we are individually baptized into and by the Holy Spirit of God. We have a direct link, a relationship with God Himself. We also each have an identification and an authority directly from Jesus Christ. 
If you knocked on a door saying “Police! Open up!” you must have the identification that goes along with that claim. When the occupant asks for identification, it’s no good if your answer is, “well, I know a cop.” No, if you are a believer your authority identification comes to you directly from Jesus Christ, your Messiah. There is no demon that can stand against that name and that authority.
Thanks Sharon for sharing your experience with us!
Authority of the Believer - by Sharon Gakin
Authority1b1Understanding the gift and use of the authority of the believer came very late in my Christian walk. No sermons were preached, no Bible studies done, and no discussions ever came up. Somehow I sensed it had something to do with power over Satan but I wanted nothing to do with Satan. I knew he worked in our lives but I figured as long as I avoided evil, I was safe.
Wrong. That first sermon on authority opened my eyes to the power, necessity, and ease of its use. The battle before time even began centered on authority: who is in charge? God or Satan. Of course Satan lost that battle but retained an earthly domain where he could work for a short time.
That hardly seems fair to us weak humans, but Christ did not leave us defenseless. First, He limited Satan and his cohorts to work ONLY by permission. If God draws a boundary, he cannot cross it. The problem comes when we fail to recognize the permission we’ve granted by default through our ignorance, apathy or sin. 
As joint heirs with Christ,  we receive what He has: authority over heaven and earth. The disciples received this authority early on (Luke 10: 17, 19; Mk 16:17; Luke 10), therefore as disciples, we can receive this also. 
Authority without power is worthless but we receive power with the Baptism in the Holy Spirit. We are equipped. Equipped to forbid or defeat demonic harassment.
Satan’s best weapon is to convince us that he doesn’t exist. Close behind that lie is the idea that he bothers only bad people with obviously bad temptations. Wrong again. Besides disguising himself as the best thing apart from power steering, he functions best as an opportunist. He capitalizes on our emotional and physical weaknesses and our circumstances. He usually steers clear of the spiritual realm because he knows he can’t compete with the Holy Spirit’s power in your life.
Recognizing when and how to use our authority takes practice. What we often assume is our flesh operating in a situation can quickly escalate into demonic interference, brought on by the opportunity our flesh presents. He can escalate a situation, but only if we let him. Fear and confusion mark his intrusion into a situation. A simple argument that gets out of control leaves you baffled as to why you acted that way and even what the whole thing was about.
One day my husband and son allowed a conversation to escalate into a shouting match. I was sick of these so I stomped into the kitchen and TOOK AUTHORITY over my house. “In the Name of Jesus, I command the spirit of argumentation to get OUT of my house!” It stopped. All three of them left. It’s rarely been harder than that.
Beyond causing relational trouble and chaos, Satan attempts to create genuine fear. When he knows he can’t hurt us, he will render us ineffective for Christ by fear. He’d love for us to rehearse and share and fuss over such encounters. Don’t.
I returned from a week’s vacation to find my large wall clock on the floor. Next day, a picture over the mantle hit the floor. Now I was suspicious. I had never encountered unexplainable problems but I knew this wasn’t normal. Then my bedroom light began blinking erratically. The final blow came when the large painting on the wall behind my bed slid to the floor as I sat in bed reading. Now I was mad, very mad. How DARE a demon enter my territory! I took authority and ordered it out. I amazed myself by not being the least afraid. It was all grace. 
The demons changed tactics to something more up close and personal. Odd ticking noises started at the foot of my bed. It was annoying and I got mad and ordered them out. The next night the clicking came closer until it was two feet from my face. Now I was REALLY mad! I yelled,”In the Name of Jesus GET OUT! Get out of my room, my house, my mind, my emotions. You have no authority here. Jesus Christ is the highest authority in my life and on the basis of the authority He’s given me, I command you to get out!” They never returned to that house.
I have used my authority when I could hardly croak out the eviction command, when I was so depressed or sick or weak that I couldn’t get out of bed. It works anyway. It’s the power of the Holy Spirit, backing us up, not the strength of our voice or our anger. Rejoice that God has so fully equipped us to live peacefully without harassment!