The idea of separation from God MUST ALWAYS lead to a physical universe, bodies which suffer, and death.
Physical matter is the CONSEQUENCE of believing in separation, causing there to be illusions of separation, which gradually intensify and become more extreme and differentiated, to the point where it turns into what WE call physical matter.
Physical matter is the solidification of the idea of separation. It is the idea taken to its extreme, yet completely logical conclusion. If there is separation from God, there is sin. If there is sin, there must be death. Death will be expressed as the pursuit of making the illusions ever more heavy, dense, attacking, unlike each other, at war with each other, and eventually will produce an entire universe of physical matter.
The objects in this physical universe will also not have completed the ego's "thought" of separation, until they have coalesced further to produce physical bodies, which will then be used to bind the Son of God to the body, and to then attack the body to kill it to try to COMPLETELY DESTROY the Life of the Son of God. That was the purpose of the whole idea of separation to begin with, and death - physical death in a physical world - is the completion or enactment of that idea.
A physical universe HAD to arise from the tiny mad idea. Illusions HAD to continue to fight with each other, because the establishment of sin demanded that there be punishment. The conflict produced by the idea of separation was automatically a state of WAR, and this war HAD to play out, and in doing so it led to a huge fragmentation of the mind, a diversification of illusions, and eventually a THOUGHT FORM which we regard as physical matter. The entire physical universe is a NATURAL RESULT of the idea of separation, and is all that COULD come from it.
Physical matter is nothing more than a very strong illusion. It is a "thought form". It is a very BIG thought of separation appearing in the mind of the Son of God. In all its ways, it is designed to cover up awareness of God and to block sight of the truth. Bodies are a specific outcome of the logical conclusion of the ego thought system, demanding a concentrated target to receive punishment in the dream, and their destruction is the "success" or final statement that attempts to make the illusion COMPLETELY REAL. Or more succinctly, it is the nail in the coffin.
All of this is illusion. All of it is thought. It is just an IDEA. It's an idea of being separate, and therefore dead. As dead as death could ever possibly show up or seem to happen in illusions. The most intense, believable, seemingly real death possible. To use it seems very real, but it is not.
This is the metaphysical truth of A Course in Miracles. Separation from God results in the eventual, inevitable "manifestation" of a physical universe, a universe of death and destruction, simply as the most extreme expression of an illusion of being separate possible. Regardless of whether the Course text itself has used the term "physical universe", this is still the truth about this place we inhabit. It is the lower end of the dream of death, and physical matter is a death thought.
And yet, none of it is really happening because separation was never really possible to begin with.
The physical universe is an ILLUSION. God did not create it or make it. OUR idea of separation made it.