The soul?
The soul does not exist. Or it exists only within a theological framework of things.
Soul is that part of our person which we hope will never die or cease to be. Soul is that part of us that if all else is taken away(i.e legs, arms, freedom, etc) then we still have our soul. Soul is never changing. Soul does not become, but is–separate yet part of the universe.
Basically, soul is a hopeful construct. The synonym of which is SELF.
It can be assumed, with some substance to the assumption, only in a theological framework. Like Free Will…and all the other concepts which the self is taken as a given.