This isnt intended to be a full study on demons. just a few verses for a platform to launch from, but a story of a confrontation with real live demonic posession that I was involved in, and including the actual conversations with the demons.
In Acts 16:16, we have the following illustration. As Paul and Silas were going to the place of prayer, they were met by a slave girl who had a spirit by which she fortold the future. She followed them proclaiming," These men are the servants of the Most High God, They are telling you the way to be saved".. (everything she said was accurate) yet it troubled Pauls Spirit and He recognized by his troubled spirit that it was demonic. He turned and spoke directly to the spirit, saying, "In the name of Jesus Christ, I command you to come out of her", and at that moment, the spirit left her.

Its interesting to note that because Paul was a temple of God by way of the fact that he had the Holy Spirit indwelling him, consequently he had no fear of the demons. Also, the demons both feared him and obeyed him. based on Paul doing the commanding in the name of Jesus.
By way of background, the greek refers to the demon who foretells the future as "Python" demon. The specie of snake who "constricts" are know as pythons. Note the parallel here. The Python demon foretells the future to excite the listener to gain foothold, but its ultimate end is to "Constrict". Constrict is precisely what takes place in demonic posession. It supresses the abilities of the person it occupies, mental, vocal, etc and "takes over" the facilities once in posession. But in most cases, they dont want to totally control the person. They want to "guide" the person so that they can implant thoughts and ideas that defeat Gods plan and the person will think its their ideas.

Websters cites "pythoness" or "Pithanis" as a "soothsaying" (or one who foretells the future) demon which posessed a girl meaning also "ventriloquest" or spirit of divination"
The greek Scholars who wrote the footnotes for the explanation of Acts 16:16 say this. It was common for both jews and greeks to use the term, "servant of the most high god" and was likewise used commonly by demons. but it was never used of God in the new testament by either jews or christians. A Python spirit was a mythical snake worshiped at Delphi and associated with the Delphic oracle. The term Python came to be used of the persons thru whom the python spirit spoke, Since this person's speech would be involuntary,the term "Ventriloquist" was also used to describe them.

( Matt 17:14 ) this was a spirit that caused seizures and great suffering and would make the boy fall into the fire or the water. note that the father thought he had a seizure, yet Jesus rebuked, not the boy, but the demon in the boy and it came out immediately. ( The verse, "Some unclean spirits can only be cast out by much prayer and fasting" is included in some but not all manuscripts)

When In Daniel 10, where Daniel was praying and Satan was blocking his prayers from getting to God. Satan held up the prayer for twenty one days, while one of the angels contended with him, and finally the mighty arch angel Michael came to help him defeat Satan. now when you see in Revelation the mighty things that angels can do, this gives us some hint of the power of demons, and where your authority has to come from in dealing with them.

A case in point, occured years ago when I was confronted with a case of demon posession. We bought a mountain hot springs resort and converted it into a Christian ministry. We opened it to all churchs to use for retreats, free of charge and many groups came to spend a week for revival etc. One week we had a group of about sixty persons there from a nearby church, adult leaders but many college age persons. During the final days, they were going to have a communion service and those who were led would give their lives to Jesus. This was held in a large dining hall we had there that would seat well over a hundred people. I was at the back in the kitchen listening and to take care of any needs they might have and just as communion started. A young lady in her early twenties, started moaning louder and louder. then started crying, and saying, "Why did He have to die". Oh Why did He have to die". "I see gold leaves on the cross".

Nothing wrong with the message, right? Then she switched to tongues, and was speaking in tongues and crying, and it distracted the entire communion process. The Pastor and the youth leader stopped and after a few minutes of uncomfortable pause, another college youth stood up and said to the pastor. "I discern that this is not of God". Some of them started to get frightened and the pastor came back to where I was and said, " I dont know how to handle this or what to do. Is this demonic? or real, and how do I handle it" Several months before, Circumstances had developed that gave me a sudden interest in how the christian handles demonic posession and I had done considerable studying on the subject, but mostly just studying the bible and how it was handled there. I told the Pastor, "I dont know either, I have never dealt with it before but we have all that is needed to deal with it. We have Jesus, and He who is in us, is greater than he who is in the world, so lets just wing it, and depend on the Spirit for guidance. I suggest you have all the other people go over to the lounge away from here and be in prayer for her and for us, and we will stay and deal with it." He did that and after they left, the Pastor, the youth leader and myself remained. I sent and had my brother come to join us. (middle of the nite) I knew if he didnt see it he never would believe it. lol anyway, the lady was still crying in tongues as we approached. I tried to talk to her, ask her questions, and every thing I said, she just ignored like we were not even there. Finally, assuming it was demonic by the sense of evil that you could feel, (and feeling kind of foolish) I addressed the demon directly, just as tho the lady was not there. I made it a direct confrontation with no wriggle room and I said, "Unclean spirit I command you in the name of Jesus Christ stop speaking in an unknown tongue and speak in english in your own voice . it stopped immediately. It was probably as surprised as I was. Encouraged by this, I asked him his name. I got no response so again I demanded in Jesus name to identify himself and the grounds for entering the lady. Suddenly the voice switched to that of a man sounding voice and the chills just crawled up my spine. He gave me his name and why he was in posession of her. as it progressed, we discovered that she had seven demons and each had to be cast out one at a time and by the same process. We made each demon before he was ordered to leave, identify who else was left, so we knew. They gave many strange names like "praying without God", "Confuser", "Liar", "Deciever" etc and indicated that they had gained access thru the lady playing with a ouija board. they said that was summoning them because she needed a helper. They claimed they were not evil but good spirits here to help her, called themselves, "spirit guides" and claimed they were her friends. I told the first one that they were not of Christ and consequently they had to leave. It got very beligerant and started screaming threats at me, saying they could easily kill me if I didnt leave them alone. I told it that I was protected by the blood of Christ and they couldnt touch me, and demanded in Jesus name that he leave. He immediately switched tactics. and said, OK, I know you belong to Jesus and that I dont have power over you but please dont send me to the pit". The pit sounded to me like a fine place for him to be so I commanded Him in Jesus name to go to the pit. It started sobbing and was terrified. saying that the light was to bright, that it was being blinded by the light, and please dont make me go. screaming, "I cant stand the light". I commanded it again, and the screams got louder and louder and then with just a blood curdling scream, it left and the lady just slumped in her chair. face covered with perspiration. I called the next one forth and the same thing happened all over again. each claiming to be her friendly spirit guide. During this process I asked them questions pertaining to statements they made. one said they only followed their master. I asked who their master was, and it said "Satan is. he is our leader" I asked him what he thought of Jesus and the face screwed up in a grimmace and it screamed, "We hate Him" I asked it why and it said, "because he steals our people" When we prayed silently to Jesus we saw no change in the demons other than they obeyed reluctantly but as tho they had no choice. but when we prayed out loud. they screamed in agony and pleaded with us to stop.
I got to the sixth one who said he was the last one. For some unknown reason I didnt believe him so I pressed him hard, finally, he said, "well, there is only that little weak one left but he is harmless". After the sixth one left, I called the last one forth, and again demanded in Jesus name to know his name, and why he was there. He gave his name as "Destroyer" and said that if the others failed, that his job was to convince her to kill herself.
After this one finally left, the lady just started jumping up and down with joy and praising God for delivering her. She told us that she knew what was going on all the time but they had control of her including her vocal cords and she was paralyzed to act on her own. She said that with each one who claimed they were the last one, that she was terrified that we would believe them and leave some behind and she wouldnt be delivered. That she had stayed with the christian group cause she felt safe there but that tonite she had decided to give her life to Jesus during communion and they were putting pressure on her not to. Working on her doubts and fears of what would happen if she did. As a last resort they had started disrupting the service thru her to keep her from it.

I learned some time later that she had accepted Christ as her savior and was a very alive and dynamic Christian, the those who knew her said that she had an amazing gift for discerning spirits. She could sense it if she was in the same room with them.

I learned much about the spirit world thru this experience. There is divine power available to the person who is indwelt and controlled by the Holy Spirit, but its important to know under what circumstances to invoke the power in Jesus name and not use it frivolously in circumstances that dont call for it. An unclean spirit will usually disguise itself as the person it indwells, to either confuse and retard the salvation of the person, or cloud the message of the cross and use feelings of inadequacy, guilt over past sin etc to keep the person ineffective, once they are redeemed. A person who is interested in the supernatural can easily become demon posessed if they are not a Christian. A Spirit filled Christian can not be possessed but can be oppressed, or harrassed. The demons ability to oppress or harrass is solely dependant on the gullibility of the Christian. If the Christian doesnt recognize Satans ploys, he will be decieved into thinking that it is his own nature, weaknesses, failures, etc that are whats defeating his witness when in reality, its the enemy convincing his mind of it. The "Guilt Trap" is one of the Christians worst enemies. Demons have no power over us. only what they can convince us they have. They are terrified of the Christian who knows their position in Christ, and are secure. This is why scripture says that "According to your faith, be it unto you". One had asked me to let them find a new home. I told it there were no homes available here, that we were all christians. and it responded, I know there are no homes open here but we will go far far away. They worked entirely on bluff, but as soon as they saw that you knew your position and security in Christ, they not only switched to pleading and asking, but were really afraid. They knew the power we had in Jesus name even before we did. It seemed they couldnt lie about something demanded in Jesus name. They were in deadly fear of going to the pit, and highly desired to indwell a human. you could tell how close they were getting to leaving cause the entensity of their crying and screaming would increase and their whole concentration was on the "light". like, "I can't stand the light, please take the light away, it hurts. Please stop, I cant stand it," and then with a mighty scream they were gone one at a time. when they were finally all gone, the lady's face was transformed from the most scary thing you ever saw to beautiful. If you have ever been in the immediate presence of demons you will never forget it. the chills run up and down your spine like your hair was standing on end. You know that you face a power that is many times what you are. Your only hope and defense is in Jesus and his protection, and its your faith in that protection that protects you.
Let me add a note here. This is one of the reasons that God tells us to "test" the spirits to know if they are of God. there are three recognized types of tongues. the one the bible describes as one of the Gifts of the Spirit and given out by God as "He" chooses for the edification of the church, then there is a form of Glosalalia that can be emotionally produced by a person, and finally, there are demonic tongues. Its very dangerous to just settle for "a tongue". Ascertain its of God or dont accept it.This, by the way, is not to be confused with the Baptism of the Holy Spirit which is required of every Christian. .
Dont ever make the mistake as I have heard so many people do, of badmouthing satan or demons and calling them names or being frivilous about them. They have unbelievable power. one small person who is demon posessed can pick up a full sized man and throw them across the room. Even Michael the arch angel when contending for the body of Moses, had an awe and respect for the power and abilities of Satan did not dare to bring a slanderous accusation against him but said only "the Lord Rebuke You". We must never forget our place. we are servants. We have no authority but Christ. We dont have any power because we are a christian. We have Jesus who has power that he can utilize thru the Christian. Dont get these confused. Its easy to do and dangerous and if we forget that, we forget it at our peril.
He doesnt give us power. He is our power. No need to ask Him for faith, hope, courage, love, etc. that makes a distinction between what He is and what He gives. He 'IS" our faith, hope, courage, love, etc. Its He, that we glory in, and lift up. not what He gives. For the Gifts of the Spirit to function properly, its important for the members to know this. He is the head, He calls the shots. He coordinates the Church members. Dont organize Him out of business. He indwells us in all his fullness. All power in heaven and earth was given him, and when you have Him, you have all there is to have. You need only to release what is already inside of you. You cant live in the Fleshly nature of the natural man and just add Jesus to your agenda. You will never see Him come alive in you till you are His. Willing to die to self and everything you have and are, in order to become what He is. His plan is perfect. He is sufficient for every need. If you dont find that to be true in your life, then look to the areas of your life that are not surrendered to Him. Thats where your problem lies. You dont have to beg and plead for Him to empower you, give you this and that. He is more than willing and even anxious to fill you with all that He is. but he does it by releasing His spirit into the areas of your life that you vacate for Him. The spiritual truth here is that He never withholds, Its always you who block.
A very important truth is never keep your eyes on your sins, attempting to correct or stop them. All the time you spend on this, you spend in defeat. Keeping your eyes on Christ, the author and FINISHER of your faith is imperative to grow in Christ. Along this same vein, dont get sidetracked by a deep study into the supernatural. If and when you need knowledge God will supply. The fact that the Gods Spirit equips us for all He demands of us is ever present, but rarely more so than in ministry where demons make an appearance. As in banking, you learn to recognize a counterfeit bill by thorough handling of the genuine, a thorough knowledge of God thru the revelation of the Holy Spirit enables you to recognize that which is not of God.
Satans work in your life will always be to diminish Jesus. Many people claim to know God personally, follow him, etc but deny Jesus.

You can worship God to your hearts content. spend days and nights on your knees, all to no avail. God put his entire hope of humanity on the shoulders of the Jesus, the Word incarnate from eternity past, who was with God and was God. He will reveal himself thru Jesus only and what He did on the cross. If He is your substitute, you are Gods child based on that alone. God sees you only thru the shed blood of Jesus that cleanses you of all sin. with out that, He can not look upon you. Jesus spent much time tryng to explain to the disciples that All of God that there is to know is all revealed in He Himself. and He only. If you dont access God thru the Christ and the cross then you dont access God period. What we think of as our freedom is in reality our bondage that we are oblivious to, due to our eyes that are clouded and our ears that are deafened and our mind closed till the Jesus sets us free. In Him only is freedom. Then and only then are we transfered from the kingdom of darkness to the kingdom of God's dear Son. Finally, never, never live in fear of demons. awe maybe, respect for their abilities and power, maybe, but fear? never. You are positionally seated with Jesus at the right hand of God right now. Your faith forces them to have to get thru Jesus to get at you. You are the Kings kid. part of a royal priesthood. Your as secure in Jesus as Jesus was as a baby in a manger with the entire nation and king looking for him to kill him. Just dont make the mistake of getting out from under His umbrella of protection. Our God is a mighty God. He lives, and He lives in us. We have nothing to fear but fear itself. Dont give the enemy an inch. stand your ground. You do this by "putting on Jesus", Who not only reveals Himself thru love, but it is He, Himself, who "is" your sword of the Spirit, the shield of faith, the helmet of salvation, breastplate of righteousness. And thru all this, shines love. Hold the ground. We do all this thru our Jesus, our redeemer, who is our substitute, our propitiation, our "payment in full" to God His Father. He alone is our power, strength, hope, and final salvation. Thanks for your time.