This is familiar territory here but I've been challenged elsewhere on my view that advaita or non-duality is a limited understanding of the world, and thought I might pass on my response here. Roughly speaking, for those unfamiliar with this philosophy, advaita states that Brahman (The Divine Self, you might call it) alone is real and everything else is, in the words of Shankara, its principal exponent, ‘neither real nor unreal’. It states unequivocally that once you see things correctly there is no difference at all between the soul and God (Atman is Brahman) so the individual qua individual has no proper existence. That means nothing else does either. So advaita denies any integrity to anything except formless being. In its eyes the soul does not become one with God, and so is divinised or made perfect as in Christianity. Basically it is God who is not personal (except as Isvara, a lower form of divine being still operating in the world of maya or phenomenal existence), but purely impersonal.
This is just a brief overview of advaita Vedanta, and purists would probably throw up their hands in horror at what it omits, but nevertheless it contains the essential substance or gist of it which is that absolute reality is pure, impersonal consciousness and no more. And that is what you are too. There is therefore no room in this scheme of things for the notion that God is Love. There is no room for creativity or any kind of growth or progression or development. Instead of all things being eternally made new, all things are eternally the same, static.
Now, advaita is very close to the truth which is why it is so attractive to many and has so many adherents nowadays. However it leaves out the real beauty and wonder of creation and existence because it separates absolute and relative, more or less discarding the latter as surplus to requirements. But the glory of life is that the whole is more than the sum of its parts, and it is only through spirit immersing itself fully in matter that this can be realised.
There are other versions of Vedanta such as the qualified non-duality of Ramanuja and that is much more in tune with reality in my view. It sees Brahman as a Divine Person with Divine attributes instead of an impersonal, featureless Absolute. Consequently it asserts that individual souls retain their distinct identity even when inseparably and indissolubly united with God. This is precisely my experience with the Masters who were both individual and universal in consciousness and presence, and it is surely a richer view of the spiritual life which implies it should be true since reality must be greater than anything we can conceive.
My interlocutor rather grandly claimed that advaita cannot be accepted by the rational mind and so can’t be rejected by it either, implying that it just is true and you either see it or you don’t. Faith is not involved. I take the opposite view. I think advaita actually comes from a very intellectually based approach in that it argues from a to b, and it doesn’t really take into account any kind of deeper faith or intuition at all. That, as I say below in my reply, is one of the reasons for its increased popularity today in our reason based culture. And that also is the reason for its limitations.
Anyway here is the reply to my challenger.
You say that advaita sums up the totality of truth and is not an intellectually constructed philosophy, but it has no explanation for this whole world of creation which it simply describes as a not to be understood mystery. Subtler philosophies can accept that what God creates is real and has a purpose, and can see that reality is the integration of being and becoming not restriction to being alone. Thus the One and the Many both exist as part of the whole. Fundamentally advaita denies the many which is why it is reductive. I know it gives the many provisional reality and accepts the existence of Isvara but neither are given any real importance or significance once realisation is attained. And even before then they are regarded as the products of ignorance.
Thus advaita basically denies the value of relationship because it fails to see that both duality and non-duality are true. And relationship is why there is something rather than nothing. This is why the idea of God being a Trinity, three in one, is a higher concept than simple advaita or one in one. Of course, there is only God and, of course, the goal is to realise that in oneself but what God creates is real not neither real nor unreal which, frankly, is just a piece of sophistry. It may not be real in the same way that God Himself is as it has no reality apart from Him, but He has given it reality and, in the case of human beings, autonomy too.
And actually to say, as you do, that advaita, or non-duality, cannot just be accepted or appreciated by the rational mind is not, I think, true. One of the reasons for its current popularity is precisely because it has a certain rationality to it. After all, what could be simpler or more rational than to boil everything down to one? You might even say that the current belief system of materialism does the same and, indeed, there are grounds for comparing the two. For in just the same way as materialism denies spirit so advaita denies matter (to all intents and purposes), seeing it only as maya. The truth is there is no knowing God without bringing together the two poles of reality which are split apart and consciously reassembled precisely so that God may be known and not remain a hidden treasure.