They avoid calling it a soul, though, and don't ever mention that. This one goes full in on that. If they had done something similar but called it a force thing, I'd be happier with it. If it wasn't a Star Wars thing, and had been written better, I'd also like it. But as it was, it was shit."life essences".
"luminous beings we are not this crude matter"
"One who has returned from the netherworld of the force"
The existence of a non physical soul or essence is expressed clearly in the movies.
Oh, and speaking of bad books, there was one, and I might be referring to the wrong book here, that was just badly written. I think it was the one with the other Emperor's hand, and the Solo's are all visiting a planet with her on it? I could be wrong though.