When we talk of duality, non-duality, pure-non-duality, we're talking concepts.
Duality means polar opposites (good/bad, right/wring, up/down etc)
Non-duality usually means both opposites are one thing. This also usually means the opposites still exist, ie the world is real, but it's all one thing. Close to a Buddhist teaching for example.
Pure-non-duality typically means the world doesn't exist at all, ie neither opposites exists. Instead, it's contrasted against "God". ie, only God exists.
While the Course DOES teach "there is no world", there is a problem with saying it's pure-non-duality.
If we're being really, really pure about it, if it's logically true that only God exists, it is impossible for God to create, impossible for God to have a son or to create heaven, its impossible for there to be a sonship, there could not even have been a dream of death, and if there were a dream of death God would now have to be the one dreaming it.
That also means, if there is only God, that God is dreaming of death, God is dying, God is stuck in a body, God is "learning" (ie lacking), God is not whole, and God is an illusion.
That's a pretty big problem.
That's what pure nonduality really indicates if you are being REALLY pure about it.
At times Jesus does say things in the course which could imply otherwise but you have to be careful to discern what level he's talking at. When he says, "God is, and then we cease to speak".... he's not saying, God is... and there is nothing else... he's saying WE as individual creations cease to speak and we become one with - sharing with - the allness of God, but still retaining our individual free will.
It's useful up to a point to say, there is no world, only God exists. But if that's the scope of your grasp of the logic, then you're falling short. It puts God in a box, all by himself. And in that box, there is no creation, there is no expression or extension, there is no son.
Pure-non-duality means God does not even have one son, yet alone many. That's a problem. Without a son God is the one dreaming and dying, which is ridiculous. Without a son, God is a sinner and a separator, which is ridiculous. Without a son, God has no effects, therefore he is not causal, therefore he is not permanent, therefore he does not exist. That's a completely logical conclusion that you should come to if you really purely believe in pure-non-duality. What started out seeming to say only God exists, MUST mean God does not exist at all.
In order for God to have in any way at all a "son" or a "creation", something which is technically not 100% equated with Himself, it has to be possible that what God is does not stay inside a nice theoretical box. For God to create, and for God to cause an effect, and produce even one son, there has to be what the course calls a "natural grand division."
A "world", as ACIM defines it, is a natural grand division, or a projection outward, from God. God is complete in and of himself, but when he extends Himself to create, He creates something which is - in a sense - "outside of His own completeness" - an "addition" to what exists. Reality is increased by creating/sharing. ie It's talking about heaven/creation. It is "divided" from God in a natural way, which is normal and healthy. It all hinges around cause-effect.
God is cause. God produces effects. Effects of God are creations, which are expressions/extensions. The course says, "nothing real can be increased except by sharing." God has to share, meaning, there is some room here, or some freedom. It also says, that God gave his sons (plural) free will, which was necessary in order to allow them to create freely. The aim was that naturally the sons would create more love and joy and the kingdom would expand. It's only when sons mis-create that they go into separation dreams.
Since God is causing the Son, and the Son is an effect, and the Son is not causing God, there is a "natural" division in terms of roles or functions between God and His Sonship. It is natural. "Separation", in course terms, is an un-natural division. Division between God and Sonship is natural. It does not mean the same thing as separation. It does not mean there are walls up between each son or between sons and God. It means there are many individual free-willed souls each sharing fully and freely and openly with each other and with God.
Getting off topic slightly. But you can see that in order to allow for God to be alive, to be creative, to express and extend, to share, what God is MUST be more than a self-contained box. There is nothing "outside" of Him as such but souls still have free will within the scope of God, and share God. You can't really technically call this "pure non duality", because there isn't a duality but there ARE MANY SONS, and many creations, and many thoughts of God, and the sonship has many parts. There are more than 250 statements in the course pertaining to God directly creating multiple sons.
A multiplicity of sons is hardly in keeping with the idea of pure non-duality. It's not the same thing. It's not a state of "there is only God". It's a state of "there is god and god's creations." It's not a singularity. It's not a concept or a theoretical box. It's alive. It's creative. It's expressive. It's more than ego logic can describe or understand.
This is why the course is really not pure-non-duality. In a general broad sense, yes, it is, up to the point where you really take a look at heaven and God and creation and the sonship, and find out that there are in fact many parts to it. It's not just one big "blob". And each soul IS endowed with free will. Will is free when it chooses to extend freedom and love. It becomes blocked when we will against God's will and therefore will against our own will. That's what victimhood is all about - attacking ourselves with our own will. It's also the secret to salvation.
If you want ACIM to be pure-non-duality, you're not looking closely enough at the facts. God and Son are not one single thing pretending to be two. God does not dream. God has not separated from Himself. We are the ones who are responsible for dreaming of impossibilities.
There is one other big problem with trying to fit the course into a pure-non-duality model. The fact that in pure-non-duality there are no individuals and no individual free will. In pure-non-duality there are no souls. There is no permanent "self" distinct in some way from others, or naturally divided. That means, the pure-non-dual teachers constantly tell you that you do not have a self, or that you are not an individual. It is BULL SHIT. God created many sons and gave all of them free individual will.
Quote: "In the creation, God projected His creative ability from Himself to the Souls He created, and He also imbued them with the same loving will to create. The Soul has not only been fully created but has also been created perfect." - ACIM
Quote: "The world (heaven), in the original connotation of the term, included both the proper creation of man (souls/sons) by God and the proper creation by man in his right mind (his own free-will creations). The latter (the son’s ability to create) required the endowment of man by God with FREE WILL because all loving creation is freely given (God gave us freedom). Nothing in these statements implies any sort of level involvement (no separation)or in fact anything except one continuous line of creation in which all aspects (each aspect being a son of God with free will) are of the same order." - ACIM
You DO have a soul. You ARE an "free individual". You may not have an EGO. Having a separating ego is not the same thing as being a free-willed soul. Ego means putting up walls and unnatural divisions between you and others. Absence of walls does not destroy your independent freedom, it simply allows you to share fully and freely with others. To be one with them, without losing your own soul.
The peddlers of pure-non-duality peddle "you do not exist" paradigm, which leads many course people to believe they are supposed to deny themselves. It in fact produces censorship of the soul and leads you to believe you are supposed to be getting rid of yourself. It actually results in a belief that the soul is supposed to DIE ie not exist. That to be in God, you cannot be a self in any way. That to be awake, you must not have any sense of existing individually.
Also if there are no souls and no individual freedoms, then you are literally responsible for the shitty choices that everyone else makes, they are literally you, and you are just as dead as the person who just died. It's ridiculous. It IS true that you share a oneness but you simultaneously have independence. This is possible in a holographic model of heaven in which the all is in every part, ie God is in every soul, and yet each soul is distinct and whole and complete in and of itself. This produces a state of simultaneous sharing with the whole AND independence. This is not in any way a pure-non-duality teaching.