Hi Dnester, this is really bothering you and I've dealt with this for years so I'm going to share how I deal with it. Your psyche may be different so you may have to find your own way of dealing with it. Actually I'm going to give you a run down of as many things as I can remember until I came to my current way of dealing with it because one of those may suit you better:
My starting point is to take the veiw that demons are not real. And I still believe that but I don't expect delusional alters to believe it, its theirs not mine, which is how I stay relatively sane.
1. Take medication (didn't work because some alters are suppressed and I lacked emotions to a point I felt no connection or enjoyment in life so its my last resort, least ideal option but I did try it).
2. Keep telling them they're not demons or from hell or been to Hell. Mine prefer to say they've been to hell - nearly all of them except Peter and Mandy and Karen. Peter is Buddhist, Mandy is a child and Karen is a witch or a pagan so they don't believe in Hell. Beth doesn't have past life memory or claim any particular religion, she's agnostic and doesn't particularly believe or disbelieve anything.
So I tried to keep telling them they're not from hell and learnt other religions and tried to say its impossible to know what's right or wrong but it got me precisely no where.
3. Ignore. Or just say "OK whatever. Who cares. Big deal. Tell me something more interesting" That didn't help.
What I do now which stops it: I let them tell me all about hell. "No-one" literally just came back from hell in the last few weeks. I say "stuck in a trauma memory" she says "went to hell because I did bad stuff" potatoe /potarto. She did commit a few minor crimes when we were younger. It's about gett her to forgive herself and let it go. It's about her accepting the trauma that happened to her, that things are not her fault. It's about getting her functioning in a helpful, life fulfilling way so she avoids past mistakes.
The Twins say they're basically demons. They worked in hell. They say there's a massive spiritual battle and the concept of heaven and hell is scewed by the Christian pantheon starting with the Jews. They say Bal (the devil) is a fire God and the Christian "God" was El the God of air. That mankind made a grave error of judgement to demonise Bal and the battle is to restore balance. Which kind of agrees with Wiccan lore, witch lore, that Karen believes. In Wiccan lore Hel is a goddess who carried the soul from death to birth which is a very painful process. And of course in Wicca there God's of earth, air, fire and water. Her disgruntlement with Christian pantheon is that they caste out the Goddess. In the Christian pantheon the Goddess is the holy ghost and she finds that incredibly offensive. So they're kind of on the same team but for different reasons.
Rose is a Christian. She believes in Jesus. But her and Patrick say they have been to Hell and Patrick carried Rose out of hell. The other day Patrick ended up back in Hell and Rose had to go get him.
So I let them tell me all this stuff and I don't disagree with them. I actually find their stories interesting now rather than disturbing. When I would get hung up on it being delusional and disturbing it was difficult to deal with it and upsetting and I was in constant battle with myself. Now when Rose says she has to go get Patrick from hell I just wish her well and back safe and sound. It's much more peaceful than arguing with myself and I get on with real life.
The worst one is when they tell me I'm actually already in hell. Not as a figure of speach but I've actually somehow slipped dimensions and am physically in hell. That used to be awful. Now I'm like "oh, this is hell. It's not so bad. Hell is shopping mall, I can see where you're coming from. Maybe we'll just stay in hell then if this is hell" Doing that has made my life easier. I was terrified doing that would make me mad but it hasn't. I don't believe what they're saying I go along with it, ask questions if appropriate and live my life as normal. In a way it kinda makes life a bit more interesting.
The twins telling me they own companies is more annoying at the moment but I think I'll just go along with that too now because writing out how I deal with the whole hell delusion has made me realise keep arguing isn't always the best option. I think I've found that more annoying because I can prove who owns a company but I can't prove there's no hell and demons so eventually I went along with them. But I decided I'm going to just go along with their billionaire stories now and say "oh that's nice"
Good luck with this. I wish for you to find your best way to deal with and live with this, Beth.