"The central lesson is always this; that what you use the body for it will become to you. Use if for sin or for attack, which is the same as sin, and you will see it as sinful. Because it is sinful it is weak, and being weak, it suffers and it dies. Use it to bring the Word of God to those who have it not, and the body becomes holy. Because it is holy it cannot be sick, nor can it die. When its usefulness is done it is laid by, and that is all." - ACIM
Look at the pivotal second line. "What you use the body for it will become to you."
So this literally means, the body *exactly matches* what you use it for.
This means, if just a moment ago you were using the body for one purpose, and you change your mind, the body MUST change. If you then change your mind back to how it was before, the body MUST change back as well. There ARE no other causes of the body’s condition besides the mind.
The state of the body directly matches, is tied to, and absolutely has NO SEPARATE WILL OR POWER over the mind’s choice of what it wants to express.
If the mind chooses to express beliefs in sin and death, the body will SHOW UP as a picture of sin and death.
If the mind chooses to express acceptance of atonement, the body will SHOW UP as a picture of perfection and immortality.
The body is a projection from the mind. Mind changes, body changes. Mind is cause, body is effect.
It is ONLY the belief that the body has a mind of its own, a will of its own, that it persists without your input, that it came to exist without your decision, and that it can die *against your will* - - all of which is a belief in MAGIC and VICTIMHOOD, that ever sustains the idea that the body can still be sick when the mind awakens.
There is no loophole in cause and effect. The idea that there are some effects which "escape" the influence of the mind’s causality, somehow caused by "some other power" - alien will - is a belief in *separation* between cause and effect, which is an illusion.
There are no OTHER reasons why the body can sustain sickness "on its own" or "because of the world" or "because of a pre-existing sickness". The body is ONLY ever a picture projected by the mind, REFLECTING its beliefs perfectly. If the mind changes, the body changes.
No-one dies without their own consent. The only way this is POSSIBLE is by mind having ABSOLUTE POWER over the body at all times. Otherwise, death could happen "for some other reason". It would also mean, when the mind wakes up, the body can STILL BE DESTROYED by some "other" will or force. This is impossible if no-one can die without their own consent. Their own consent is THE ONLY CAUSE of sickness.
Therefore, a sick body cannot possibly be maintained at all if the mind is free.
"A broken body is PROOF the mind has not been healed."
We cannot optionally, or technically, demonstrate sickness if we are to awaken fully to the truth. It is metaphysically impossible, meaning it is literally impossible for the body to be sick if the mind is not sick.
"Because it is holy it CANNOT be sick, nor can it die."