What do you mean by “spiritual/” What physical part of the body “remains?”
Cite?
AQre they material or aren’t they? If they are then how can they move through wall? If they are not, then how can they interact with physical objects. Also, ifr they are nort material, what are they? What is the substance of “spirit?” What physical properties does it possess? How doe it perceive light and sound without organs? How does it retain consciousness without a brain? How does it move without muscles or limbs? How does it generate kinetic energy?
Non-dead people as opposed to “dead” people? Dead people are, by definition, the corpses of physical bodies. Corpses do not move around or “make choices.” Defining ghosts as “dead people” is a non-definition.
Also, please explain how ghosts can go through walls if they are material and how they interact with the physical world if they are not. Plus you really need to explain how something can exist without being material (and don’t say “enegy.” Energy is still material. It doesn’t get you off the hook.)
I’ve never once walked through a wall. Please explain how ghosts do it. “HOW” is the operative word here. Speculations as to WHY are irrelevant until it can be shown that any such phenomenon actually happens.

