Those course students who believe they are only supposed to correct their own perceptions - perceptions of the physical world, as though the physical world is reality and you simply need to see it without judgement in order to keep living in it peacefully, are missing a major point.
If the world is real, you have all your faith in the ego and none in God. You are faithless.
Also if you believe the world is reality, you will completely cut yourself off from God's supernatural power. You will cut yourself off from MIRACLES!
Miracles must demonstrate that the ego's laws are broken and have no power over God. That cannot happen if the physical world is reality. What is REAL cannot be changed and nothing has power over it, so how can miracles happen if the world is real?
When believing this world is real, or that the things happening in it are real, you will constantly be bogged down in a state of tension, upset, reactions and suffering. It's like a heavy blanket laid across everything. Every day will be like yet another day of doing "important things" and avoiding "serious things" and worrying and fearing and reacting with upset. No matter what happens, it will seem real and you will react to it with your ego.
It is not just that your mind has "illusions about" the world. There are two separate things. There are illusions, and then there are DELUSIONS. Delusions is the belief that an ILLUSION is reality. If you weren't delusional, you would recognize and see through the illusion and not fall for its appearance. You would not believe it was real, you'd know that it was a trick, and you would stop falling for it.
So most people seem to be working on their delusions but are thinking they are working on their illusions, and that therefore when they remove their illusions "about" the world out there, they'll come to be at peace with its reality. This then justifies as whole SHITLOAD of CRAP, about how events are still going to happen, things are still going to go wrong, people are still going to get sick, and Course students are going to "die in peace", which is a complete failure to understand the truth.
Shit does not have to happen AT ALL! The world is not real, and we share and extend God's supernatural power over it. The world ITSELF is a massive illusion, and BELIEVING IN IT means you are falling for that illusion and are convinced it is REAL, when in fact it's really nothing at all.
If you believe the world is real, sickness is real, sin is real etc, you will go through every day with your mind trapped inside a heavy shell of horror. Every single thing you perceive will make you react, either strongly or subtly, but never not at all. You are SO USED to this mode of functioning that you may not even realize the freedom that you can experience by regarding and relating to "this world" as though it actually IS an illusion.
You will not take it so seriously, you will not be so upset by it, you will not react to it, you will not perceive it as attacking what you are, and you will recognize there is nothing stopping you from changing it with the Power of God. It holds no weight, it's not real, it's like just some big giant pretend 3D holographic projection pretending to look like a world. It's not even really there. And if it weren't for certain atomic forces you would pass right through it!
Only by recognizing that the world ITSELF is just an illusion of a world, not a real world, can there be ANY justification whatsoever for having faith in God, relying on supernatural provision, TRUSTING God's truth, or any foundation whatsoever for performing miracles. Miracles and truth and trust and faith and love and Heaven might as well not exist if you want to keep believing the world is real.
And the reason you won't want to give up that belief is because you have a LOT invested in it. All the objects in your life that you are attached to. All the relationships you think are special. All the history and past which you value greatly. All the places you think are special. All the ways that you've come to develop a "spiritualization" of certain things and believe they are holy. All of the delusion that people really get sick and suffer and die. That's a LOT of belief. It's a lot of faith in the ego, trust in the ego, reliance on the ego, and permission being granted to the ego. And you can't believe the ego and believe God at the same time.