Did you ever read the novel Lilith, by George MacDonald? He believed everyone would be saved. It’s been a very long time since I read it, but iirc, the ‘salvation,’ of dead sinners—even the worst of the worst—was accomplished in a strange way. To wit: they slept. And slept and slept, until eventually they were saved.
A very weird book.
I heard of it and him but never read any of his stuff.
Sounds a bit like purgatory.