First of all, be glad it is not actual demonic possession. I read some place that possession is relatively rare, but demonic oppression happens a great deal. You must constantly pray to God for strength to overcome this. Read the Bible. Pray. If the demonic oppression is causing you to sin, then go to the Lord with a sincerely repentant heart, ask for forgiveness and ask for the grace and the strength to not commit the sin again. If you are truly sorry, He will forgive you. And if you should slip and go into the same sin again, just ask God for forgiveness again and for the grace and strength to not do that sin again... Go to church every day if you can. Talk to your minister about all this. I don't know what specific faith you are, but I would make use of any sacramental they have. This could be Holy Water, or it could be chrism the blessed oil or both. I have friend who is Pentecostal who keeps the blessed oil in her home and blesses herself and her son every day. (Trinitarian, of course -- In the name of the Father, the Son and the Holy Spirit.) The devil despises these sacramentals because they come from Jesus's church. Is not superstition at all. Also, if you are allowed to have crosses in your religion (most do), then put a couple of them up on your walls. I would even sleep with one in my hands. I have actually done that. The devil hates crosses to. Finally in this regard, it you are member of faith that does not permit crosses, then get dove that represents the holy spirit and do same as cross. And if that is not allowed either, then keep couple Bibles in house and put one right by your night table or in the bed with you. Devil really hates that. Again, absolutely is not superstition. My Pentecostal friend has even anointed me with that holy oil -- of course this oil is blessed by her minister. I hope this helps. Oh-also helpful. You can say, "Get behind me Satan," just like Jesus said to Peter. And other short prayer, "Lord Jesus son of God, have mercy on me, a sinner." Again, other stuff the devil hates. Hope all this helps. Again, the first step I think would be to talk to your minister. I will be praying for you in the name of Jesus of Nazareth. Your sister in Christ, Lamb.