Separation is really about trying to do everything alone, without God. After all, if you separate yourself off from God, who was essentially doing everything for and with you, you end up in a position where you have do it all yourself. You then start to depend on yourself in every respect.
Depending on your own thinking, your own efforts to assign meaning, to figure out what things are, what to do and when to do it, making plans, making decisions, interpreting everything through your own personal beliefs, trying to single-handedly do everything without help.
It's as if we say, "I don't need God". And then we start developing all kinds of needs, lacks and limitations. And now we seem to have to fend off the attacking world single-handedly. And then we develop pride and prowess and abilities and skills and information and all manner of defenses to try to bolster our ability to survive.
But the fact is this. All of our efforts to do everything alone, has made us miserable and exhausted. It has produced every conceivable form of suffering and sickness. It has eroded all relationships and trust. It has made us seem small and weak and helpless.
We've basically tried to take on this huge burden of managing "our own life" to the exclusion of depending on God, and we've found that we're horrendously under-equipped. We've been just carrying a heavy weight of burden trying to be "the one" that does everything. And then to top it off we've framed our efforts at "independence" as something to be celebrated, complete with victories and successes, and all manner of self-appointed empty awards.
What I see ACIM telling me now is that basically, I have orphaned myself, and put myself in a position of loneliness and isolation, such that I've ended up having to carry the weight of the world. To do alone everything that I should be allowing God to do for me. It's like someone who refuses to accept any help and prides themselves on their seeming "abilities" to accomplish goals on their own.
But the course is saying hey, the Holy Spirit is here to do all this for you and through you, to mange your life for you, to look after your body and health for you, to think and inspire and heal for you. But it's going to require two things - a willingness to give up your position of autonomy, and a willingness to surrender to trusting in being dependent on a higher power.
It really boils down to a question of, do you want to be separate anymore? Do you want to be alone in everything you do? Do you really want to have to be the one that figures everything out and makes all decisions and solves all problems and heals all wounds?
The fact is this. The more you separate off from God, the less power you have. The more you isolate from help, the smaller and weaker you become. The more distance you put between you and God, the less capable you are of doing anything at all. You basically lose everything by moving away from him. You THINK that you're gaining everything, but it's really an illusion, and you end up with literally nothing. Or as Jesus puts it, you will think you are gaining the whole world, but will lose touch with your soul.
What we call an "ego" is just some soul who is trying to be separated off from the shared dependency of relationship with God. It's a self that doesn't want to share and doesn't want to be part of the whole. It's a self with an attitude problem of selfishness, autonomy, specialness and every aspect of the ego mindset that comes with that. It's just someone who is alone and afraid, lost and confused, and doesn't know how to get out of it.
The more you try to gain in terms of what you can do on your own, the more you lose in terms of what you share with God. The more you think you are becoming strong in your independence, the more strength you lose. The more you think that you are so confident on your own that you don't need anyone, the more afraid and vulnerable and limited you become.
The only thing that we're really being asked to do is to come home and rejoin the family. To stop being an outsider or a loner. To open up to sharing with God again. To re-establish your dependency on God for everything, and learn to not want to do anything alone any more. It's God's heart just reaching out and saying, hey son, I love you, come back to me, you're still welcome. Come home.
And so this whole thing is indeed like the prodigal son, running away from God believing you are so capable of going it alone, until you run into pain and misery and suffering, and then finally realize it is utterly impossible to live without him. And then you return to him, willing to surrender and let go of all efforts to do everything without him. To give up all judgment and all evaluation, all decisions and all plans, all interpretations and all meanings, and everything you thought you had to do when you had no-one else to depend upon.
Just to let yourself be a part of God again. Supported and protected, nourished and cared for, guided and directed, loved and made whole.