When the 'separation' happened, we put various forms of distance between ourselves and God. We closed our heart to God. We shut God out of our lives and out of our minds.
We then found ourselves 'cut off', disconnected, lost, alone, abandoned, as if the 'cord' that connected us to God had been severed. Now of course, this was very upsetting (and still is).
Because of this, it then seemed that we were disconnected from the SOURCE of life. And because we saw ourselves as cut off, what we were left with was the perception that we did not originate IN God. Instead, we believed we must've just come into being spontaneously by some other means as orphans (symbolized by birth).
So now, without a connection to God, we are all alone, desperate, afraid, confused, we don't know what the hell is going on, and we have very limited resources. Our power is hugely diminished, we're hallucinating, we're insane, scrambling around in the darkness trying to make sense of it all.
So without acknowledging that a source (God) is extending/creating us, we come to believe it all seems to start with ourselves as the source - that WE are the source. Thus is born the ego - the starting point of separate existence. And by this token, we have separated the Father and the Son.
What I mean is, in Heaven, God the Father extends His Fatherhood to His Son and His Son also therefore possess a nature of Fatherhood as well, by which the Son also extends Creation. The Son is a Father to the Son's Children.
Get this... When the separation happened, Father and Son were separated, not just in terms of being separate beings but in terms of their shared nature where the Son is also a Father. This now means that the Son does not SEE Himself as the 'Son' of God, he only retains the idea that he is the Father. He sees Himself as retaining fatherhood but of not retaining sonship. He retains 'output', if you will, but shuts off 'input'. So now he thinks of Himself as 'the' Father, since he Himself does not seem to have a father, and this is how the ego believes IT is God. The ego is 'Fatherhood' without 'Sonship'. In a way, you could also think of this as 'giving without receiving', which produces 'making' (creating stuff that didn't come from God) and 'sacrifice' (losing everything and not receiving at all). It is by this method that the ego then MAKES its own Father, out of itself, because it is fatherless, and this newly appointed Father is the ego's OWN version of God - its fake God, a God of hate and death. The ego then idolizes this fake God, who calls for sacrifice, and the ego now both worships and fears this (and all other) substitute for God. It should be apparent how insane that is.
An interesting bit of metaphysics there!
Anyway... So now we see ourselves as the source, which means we think that we have to govern existence, run the universe, obtain power, control everything, force things to be according to our own separate will, and act like God. Classical ego.
So.... what we need to do now... the whole point of doing A Course in Miracles.... is to heal the separation - or at least, all of the belief that it has really happened. But we DO believe it and it does SEEM real. We really do SEEM to be experiencing the horror of being without God, of being Fatherless, of being disconnected from God deep in our hearts, of having been abandoned or rejected, or being absent of REAL LOVE, of not having a SOURCE, of being without unconditional love, of having to do everything ourselves and failing miserably.
We need to HEAL this sense of separation between the Father and the Son, between God and us. And this is a very heartfelt matter. It's not intellectual. It's not just on a mental/mind level. Love is FELT and EXPERIENCED! What we really want is to experience the love of God. Period.
So to do that we need to get back to the kind of relationship, the kind of 'structure' of the relationship that we originally have with God. That means, restoring our CONNECTION to God through communion and healing and openness, being open to RECEIVE guidance and healing and love from God again (which we have been sorely missing and doing terribly without!), becoming able to SHARE in what God is offering, and to then extend it once again through creative acts (miracles), to extend the Kingdom.
Father and Son need to be reunited and set back in their proper place and arrangement where God is the Source of Life, Life has extended itself AS the Son, and the Son extends it further. This is the only NATURAL condition. The physical world's 'nature' is NOT natural. Or perhaps some people refer to this divine holy relationship as SUPERNATURAL. This is what we need to restore, for ourselves, in direct relationship with God, for real.
God loves us. We've denied Him. We need to open to receive His presence.