For many, ACIM is about self help and doing the lessons and trying to get back to a simplified idea of God/reality. But the scenario of what is happening in this world, why we're here, and what we're returning to, is part of a big picture "story" that I don't really see talked about a whole lot. At least not in fully encompassing terms.
Basically we existed as eternal beings in heaven, God's sons, and he had also created the angels etc... and everything was groovy, and then this separation thing happened, there was "war in heaven", a split, and the descent into "hell" through the making of hierarchies of illusions, levels, dimensions, worlds etc... and we ended up with this physical universe.
And now God has created the Holy Spirit and is sending his angels to guide and support and educate us, to help us to come back home to our heavenly home. Which means... drumroll.. this entire world is like a DEVICE which heaven is using as a mechanism for bringing home all of the lost souls who attempted to war against God. And the whole purpose of this world is for the lessons and learning - the curriculum, which has been set up by God, by which we might learn the truth and return willingly to cooperation with God's will, freely.
When people for example have near-death experiences they go and encounter these situations, where they are having life reviews and meeting with God and talking to spiritual beings and all this stuff, and then being sent back and "its not your time" and so on... script to be fulfilled, lessons to learn etc.... and so you get this overall picture that this world is not just some random world that we're trying to wake up from, and we're not just trying to wake up to an nice sanitary idea of "reality" or "oneness" or "non-duality".
There's way more to this story. And there's an entire foundation for "the fall of man" and how we got into this mess, and realizing that this world IS the mess we made of reality, and how we now need to clean up the mess and go home. And that means that despite all the theories that various people have, despite all the religious beliefs, despite all the concepts of why we are here, the scientific models, bla bla bla, agnostics, atheists, whatever, basically underneath everything it's TRUE that we all descended from heaven, fell in the "tiny mad idea" which really was a huge monstrous idea, are now having go through a special curriculum for salvation, and eventually will be ready to return to God's Kingdom.
So all this sort of Christian-religious stuff about heaven, making hell, believing in sin, suffering, death, illusions, trying to be separate from God, authority problem trying to oppose his will, angels helping us, there being scripts and curriculums, life lessons that are orchestrated before birth, all this stuff, it's all actually quite correct. It's all part of this huge PLAN, the atonement plan. And all because of what went on in heaven, the fall of man, the descent into hell, and the subsequent need for the atonement to correct us and restore us to awareness of love's presence.
But I think we get really out of touch with this a lot in the course community, drifting off into these intellectual models of what the course is about, vague ideas of oneness/reality, somewhat clinical God-less models, and a whole bunch of skepticism about anything not "explicitly" mentioned in the course text. We get rather narrow and start to see things through a kind of "ACIM filter", through which we filter OUT stuff that doesn't seem like it's mentioned in course lingo etc. But if you look all this stuff is in there. It lines up quite significantly with what the bible says albeit that a lot of the bible stuff is somewhat distorted. But it has the basics down.
We are part of a giant classroom, in which the atonement plan/curriculum is playing out. And this is precisely the same atonement plan that is to do with our incarnations, our themes and scripts for our lives, our lessons that we agree to, the mighty companions and angels that help us, spirit guides, the astral plane and other dimensions, and the fact that no matter what anyone in the world believes they are ALL part of this same scenario. We're all in the boat of "wanted to be separate from God" and "made worlds to live in apart form God" and are all in various ways trying to find our way back because that's what God wants.
For some it's more accepted than others. For others they don't even think any of this is true, and fixate on various other explanations for why we exist. For many ACIM is just some nice little tiny behind-closed-doors self-study "course" with very little to do with this huge big story of how we got here.
But we can't change the facts. We're living the curriculum that God established to correct the separation. This world isn't just some scientific experiment. It's not some virtual reality. It's not just a random chaotic environment. It's a school - repurposed from the hell we made, designed to lead *everyone* of *every kind* of civilization back towards the reality of heaven, our true home. There's no way to avoid this fact. We can deny it and believe other things but this is the underlying "framework" that encapsulates this whole world.
God is using this world as a device to bring us back to God. The whole thing. It's one giant school for learning, to lead us back to awareness of love - back to God, back to the Kingdom that we fell from - where we are safe in God, dreaming of exile. This world is the exile. Going home to God is the goal for everyone, regardless of how much they accept it or are aware of it. This is why Jesus calls it "the universal curriculum". Everyone is part of the plan. There are no exceptions. Even people not "doing ACIM". Even the atheists and scientists. Everyone is part of this. "The great awakening".