I once dealt with demonic oppression. It was both awful and terrifying. I could hear its voice and feel the pain and fear it pushed on me, and I went many days without being able to eat or sleep.
I came to Christ through that, but I was worried that it didnt immediately go away right after coming to Him. I would pray for Him to take it away and I didnt understand why it wouldnt go away. So one day I prayed for the Lord to guide me as I read the Bible and help me understand what I needed to learn. And I opened up to Cor 2, and I read this story here-
2 Cor 12: 7-10
Therefore, in order to keep me from becoming conceited, I was given a thorn in my flesh, a messenger of Satan, to torment me. 8 Three times I pleaded with the Lord to take it away from me. 9 But he said to me, “My grace is sufficient for you, for my power is made perfect in weakness.” Therefore I will boast all the more gladly about my weaknesses, so that Christ’s power may rest on me. 10 That is why, for Christ’s sake, I delight in weaknesses, in insults, in hardships, in persecutions, in difficulties. For when I am weak, then I am strong.
So I decided to be faithful while I endured what was happening to me. Of course, I could never have stood on my own, and after coming to Him it did become easier in ways. I was able to eat and sleep again. But I still felt alot of fear and anxiety, and I could still hear the beings voice. After I read this I decided to not try to "fight" it, but to just keep reaching out to God, asking for guidance and strength, and relied on Him during this time. And after some time all the fear and anxiety I felt went away, and I can absolutely say that I now feel completely fine and safe : p
It wasnt any ceremonies that helped me, or holy water or any of that. The only thing that helped me was faith, prayer and patience in Him.