The idea of non-duality is an attempt to describe reality or the nature of God. What is really real and really exists. At first we have the idea of duality or polar opposites. Then we reach the idea that the world is secretly "all one thing", as though all the objects are connected together by a singular "one" something.
Then we're presented even further with the idea that if we're being really "pure" about it, the forms and objects really don't exist at all, and the "oneness" beyond them is all that really exists, ie God. In this model of "pure non-duality", there is no world", and this is what SEEMS to correlate to SOME of what ACIM says. This usually leads to conclusions such as "oneness" as in "a count of one something", "its all God", "it's all mind" etc.
So various people took up the idea that ACIM is pure non-duality. But this has some problems. Let's put it this way - the idea is not pure enough. Because if this is a logical concept and we're trying to get down to the purest essence of "what is", usually you'll find that the pure non-duality folk will ACCEPT that "God has one son". There's a lot of material about God having a son - "The Son of God". And while this is accepted, it's not actually pure.
How can God have a son, at all, if there is only God? How can you even label some aspect of God - like his "radiance", as "a son"? God would not be able to have parts, or aspects, or anything you can ever attach a label too. Not even in the most vague of ways. Some people like to try to get around this by suggesting that the Son of God is so joined to God that there is nowhere he ends and God begins... while STILL keeping somehow in their minds this loose idea that SOMEHOW, you can still point a finger at this "part of God" and call it God's Son. THAT is still not pure. It's a bandaid attempt to explain it.
The problem is that if you get really pure about it, and we remove all sense of separations, divisions, multitudes, labels, parts and aspects etc... and we REALLY boil it down to "one thing" as in the traditional idea of "oneness" (the ego's idea of purity), we end up with .... there literally is only God. And that means God, sitting there ALONE, by Himself, WITHOUT a Son, without a sonship, without any creations or thoughts, just totally alone, no-one to share with, nothing to communicate with, just complete a total loneliness. THAT, actually, is the purest possible interpretation of "pure" non-duality. That "there is only God" all by Himself and he doesn't even have a Son at all. Not even one.
But many people will not want to "go there" because to suggest there isn't even one Son flies in the face of a lot of ACIM material. And certain popular teachers have taught for a long time that a) there is only one thing but b) a slight exception is made for there being a single son. This sort of hybrid mishmash of logical concepts has been quite widely accepted as a correct mapping to what ACIM is saying. One God + One Son, who is God, but isn't, but is. It's a bandaid and not logically pure nor does it match what the Course itself says.
The fact is, if there is truly this "oneness" in which there are not "many" of anything, in an effort to avoid "duality", there is **no son** there whatsoever. Not even as an aspect or expression or radiance or thought or part of God. And that leads also to the super watered-down conclusion of "it's all God" ie "there is nothing else". And that conclusion by itself has problems because e.g. the Course speaks of how a) God does not will to be alone and b) God is a creator and c) God has at least one Son and d) God created the Holy Spirit and e) God created angels and f) the Son has his own creations as well. Which is shaping up to be a lot of "parts", a lot of "somethings" that are sufficient enough to say there isn't "just" God there - that there HAS BEEN an act of creation. That something has been ADDED TO reality.
There is also an issue of freedom. If everything in reality is God and God is just being God in all of His ways, then there is no freedom in which any part or aspect has any free will. There is no way that you as a Son of God can dream of exile. There is no way that anything can occur without it being God doing it Himself, directly. And any idea of a Son must really be an idea of some kind of PUPPET that God is manipulating that has no mind or life or will of its own - no freedom at all. Which really runs counter to what Jesus tells us of the Son of God, free will, the ability to choose and the separation seeming to happen.
If you also blob it all together and say "its all God" then you end up with the alarming scenario that God therefore MUST be dreaming of exile, God must have invented the illusion of death, God is REALLY cruel, and God has attacked himself. This renders God insane, and that just isn't acceptable. Because if God could go off the rails, there is no way He would ever return to sanity, and all of existence would vanish.
It is vital that there be some kind of freedom between God and the Son in order for God NOT to be pulled into insanity along with His Son's dreaming. Free Will is absolutely vital in order to prevent this. But to have free will means, you guessed it, there MUST be a kind of "independence" or individuality, in which the Son CAN, if He so chooses, try to will against God. And this is based on the fact that God is the CAUSE of His Son, His Son is the EFFECT of Him, and God has given His son FREEDOM to SHARE His freedom with Him, or deny it. Either way, without freedom there is no free will and no son at all.
There is also another major problem with non-duality. God by His nature is love and love MUST be given. Unless it is given ie shared, it does not extend or shine and so becomes essentially lifeless. IT MUST go out and create. If God has no son, there is nothing TO love or to SHARE it with. And so love cannot love. And this means, ultimately, logically, that God is dead because He isn't LOVING. This again is unacceptable as a conclusion. God can't be dead or unloving. But to be alive, GOD MUST CREATE, so we must accept God has created ADDITIONAL BEINGS in a state of freedom.
And this is the key part that non-duality shits all over. Regardless of the fact that it destroys the sonship and ignores God's creations, it basically denies that God CREATES at all. It's the idea that God is just sitting there alone twiddling his thumbs. And this means He is not creating a son, not even one. It means there is no Kingdom. No Heaven. No HOME for the Son of God. No inheritance. It means the denial that God has a family. It denies that God's SON is a creator, AND it denies that God's son has created children. It's not conceptually a good FIT for ACIM's metaphysics.
So non-duality basically suppresses the MANY thought creations of God, denies many aspects of REALITY, and overthrows the Kingdom. It kills off God, puts a stop to Creation, eradicates sharing, makes it impossible for God to create many children, and interprets the Sonship as a collection of egos. Now, WHO exactly do you think comes up with such a concept of "what reality is like"? THE EGO. These are the EGO's conclusions, non-duality is an EGO CONCEPT, and like all ego concepts it actually NEGATES what is true and cancels or denies reality.
All non-duality models are the ridiculous FALSE conclusions that the ego comes to when trying to understand something TOTALLY BEYOND the ego. Something whose nature is NOTHING LIKE the ego, and so the ego is utterly clueless as to its nature. Non-duality is not really an attempt to define or describe reality, it's an attempt to destroy it.
At best, and only loosely, non-duality MIGHT describe "God Himself", if you could isolate Him and say, God is one whole being, PRIOR to creation. But beyond that, in terms of God being a CREATOR, who HAS CREATED CHILDREN, it totally falls flat on its face. There is no sonship without creation. Non-duality is Kingdom-denying. Reality IS NOT a state of "its all God" or "its all mind". It's all God AND God's creations AND their creations. Because you can ADD TO REALITY, reality cannot be non-dualistic.
"HE created the Sonship, and YOU increase it. You HAVE the power to ADD to the Kingdom, but NOT to add to the Creator OF the Kingdom."
"God created His **Sons** by extending His Thought and retaining the extensions of His Thought in His Mind. ALL His Thoughts are thus perfectly united within themselves and with each other because they were created neither partially nor in part."
"You should know that all God's children are fully worthy of COMPLETE courtesy."
"We are creation, WE, the Sons of God."
"And we, God's children, rise up from the dust and look upon our perfect sinlessness."
But let's back up a moment. The Course DOES say that there is only God. It DOES say God has one Son. It DOES say there is only one mind (Christ mind). It DOES speak of oneness. "Into eternity where all is one" "I and my father are one" "God has but one son" etc. And that *seems* to support the idea that "its all God". But here's the thing. IT IS all God, it IS all "one", BUT.... THERE IS **ALSO** CREATION. And all created BEINGS are LIKE God, share with God, are one with God (of the same nature, joined to Him), yet have THEIR OWN FREEDOM.
God HAS created a family of beings. God IS a creator. God DID create at least one son. SO non-duality is out the window. Reality is not some giant expanse of singularity. It's more like a womb in which God has given birth to creations, WITHIN His own being, and has given them FREEDOM. Living, whole-minded, willfully free beings. Children of God. And if that makes you uncomfortable because it "does not compute" or "it sounds like duality", too bad. It is what it is and its your job to accept it.
It's not the same thing as duality. Duality means the localization of parts which are split off and kept separate by NOT SHARING with each other, confined and isolated and different. Duality is the nature of space and time, where nothing shares. Non-duality is the idea of the opposite of that - that the differences are illusions and everything is one thing. But that too is not accurate. Reality isn't some "state" where God is contemplating his navel. Reality isn't like duality even with its many parts because they STILL are all "one" AND YET also many. And each part SHARES with all the rest and IS EVERYWHERE. "One mind is all minds."
Love is EXPRESSIVE. "Divine abstraction takes joy in application." "God did not will to be alone." And as such God has gone BEYOND the concept of "there's only one thing there". God has CREATED children. He has ADDED to existence, and your function is to add to it further. That's not non-duality by a long shot. Nor is it duality (spacetime where things are separated and limited).
God has created a Kingdom. A home for His Sons. Who are one, but many. This is what's miraculous and ego defying. Because of SHARING ("nothing real can be increased, except by sharing"), God has "made room" for beings within Him who share with Him FULLY (oneness) but who STILL retain their own souls. The soul has been FULLY ADDED to existence.
"The soul has not only been created perfect, it has been FULLY created. There is no lack in it."
After the ego is undone, after the separation has ended, after the universe has disappeared, after all divisions and artificial UNNATURAL separations are gone, when duality is no more... the children of God WILL REMAIN children of God, just as they were BEFORE the separation.
"I am as God created me".
"The Holy Spirit promotes healing by looking beyond it to what the children of God were before healing was needed, and will be when they have been healed."
"The Voice of the Holy Spirit is the Call to Atonement, or the restoration of the integrity of the mind. When the Atonement is complete ***and the whole Sonship is healed*** there will be no Call to return. But what God creates (Holy Spirit) is eternal. The Holy Spirit will remain with ***the Sons of God***, to bless ***their creations*** and keep them in the light of joy."
A Course in Miracles is NOT non-duality. It only loosely teaches that "its all ONE" or "we are all one". That's TRUE. We're woven from the same cloth. BUT, it's not the WHOLE truth. We are ONE, BUT, God as the Oneness has created many of us WITHIN His being. And this is NOT contradictory to God, only to the ego. It is miraculous. And this is because God is MIRACULOUS. He HAS done what seems impossible to the ego. He HAS created a Kingdom filled with souls, beings of light, who share everything together as one united family, WITHOUT destroying reality and without fragmenting existence.
"God, who encompasses all being, NEVERTHELESS (regardless of whether you like this or it makes sense) created **separate beings**, who have everything **individually** and want to share it to increase their joy."