Hi:
I am not sure what you mean with my interpreting ACIM, so please point out to me how that is the case. I meant merely to summarize, not to interpret. To me it seems that non-dualism is what the Course says on the most abstract level. "God is and then we cease to speak," etc. It makes it very clear that Oneness, "Heaven," is the only reality worthy of the name - other terms you could put at that level would be Infinity, Love, Eternity, Spirit, Mind, and it even makes the comment that there is no place where the Father ends and the Son begins. However on the more practical level the book is entirely directed to the process of our "returning home," from this dream of duality, which we are having while we are safely sleep, but perfectly capable of waking up to reality.
How the Course handles Maya and the making of the world is very different from other systems though, and critically so in the context we are discussing. I.e. even if Maya (the world of perception, as opposed to reality) is merely a game that the godhead (Brahman) is playing, that still grants the world reality. The subtle difference that the Course makes in this regard is that it explains the unexplainable by saying that not God (as a Whole), but the Son had this silly little idea of what if I could be separate, and in his dream now lives out the consequences of having a separate (and by devinition limited) mind, which however is still one - i.e. there is one ego, one thought of separation, one consciousness, however its nature is such that once the son thinks he is a separate individual, by a process of refraction he MUST perceive everything as individuals and he projects this out into a world of separate individualities and bodies. Furthermore it explains the difference between creating and making - i.e. the world of perception (duality) is made by the separated mind (lower case m), as opposed to the mind of God.
The operative point of this mythology is that the explicate order, the world of perception, the physical universe which we love so much to study is the manifestation of that thought of separation and differences, whereas in the Course's language, God only creates, which is explained as a process of never ending extension, while consciousness, the separated mind, can only project, in what is the son's attempt at mimicing creation, but the Course calls that "making," as opposed to creation. But to use a gnostic term, that observable world is an abortion, a still birth - the Course says about that: there is no life outside of Heaven.
Advaita vedanta fails to provide an expalanation of the same cailber, and the Course gets around it by explaining that it cannot be understood, because it only happened in a dream, and God (Reality, Heaven, Oneness) does not even know about the world. These steps account for the transition from Oneness, absolute and perfect non-duality, to a dualistic world of duality, and consciousness is the first step in that process, for consciousness is of something, i.e. the ego one it imagines being separate from God, is now conscious of God, The logic is purely that oneness must of necessity precede twoness (duality), and only one of them can be real. Therefore in terms of the Course, only truth is true and everything else is a lie, only Oneness is Real, there is no Life outside of Heaven, etc. Oneness is reality, perception is dualistic, and therefore not real, so Maya is the implicit choice of the separated mind that it implicit in the choice for separation. The Course also helpfully points out that this explanation is not completely satisfactory, but can really only be experienced whenever our mind returns to oneness.
Ergo, in these terms, BK's notion that the manifest, observable world is merely what the thoughts of the mind-at-large (which he equates to "God΅) look like to an observer of them, is equivalent to thinking that God created the manifest world and makes this approach a closet dualism, not a non-dualism. That said, I am absolutely enjoying the clarity of BK's work, which is very refreshing indeed, except that I would insert that extra step - i.e. the manifest world is the observation of the workings of the separated mind, as opposed to the Mind of God. Once I do that the whole thing makes sense, and that simple step makes it non-dualist in the end, while acknowledging that our day to day experience indeed seems to be within this very dualistic world of perception and when I shave in the morning, I still think that the face I see in the mirror is me.