Since the "soul" has to interact with the body to control it, the "soul" couldn't be a pure metaphysical “substance”, it should be physical, composed of particles/energy (which is the same, as Einstein said) or it couldn’t “command the body”.
The so-called dualism, arguing for a main difference of nature between mind (or soul) and body, imply a direct violation of the Second law of thermodynamics [see, for instance,
Harold Morowitz, The Mind Body Problem and The Second Law of Thermodynamics (
http://newdualism.org/papers/H.Morowitz/Morowitz-BandP-1987.pdf)].
Thus, as a system of physical particles, the soul would be subject necessarily to an increase of entropy and therefore to decay and dissolute on smaller particles: on other words, to death.
Moreover, at least until now, the CERN's Large Hadron Collider didn’t find any particle compatible with any "soul".
Some even say that if this particle wasn’t already found, it won’t ever be because, taking in account the levels of energy at which the body works, it had to showed up by now (
http://www.express.co.uk/news/science/771662/Brian-Cox-Neil-deGrasse-Tyson-GHOST-LHC).
I have to add this argument against the "soul" to the Op in due time.
Of course, the same reasoning applies to god. In order to be able to create the Universe, he had to have physical nature. An ethereal substance couldn’t create physical particles or changed them in order to cause the Big Bang. The same must said about his ability to make “miracles”.
But I guess that with god everything is fair game, including claim that he can change him self from a “perfect substance” into a physical nature and back again. God is the supreme chameleon.