The question about what is the Divine can be seen from two vantage points. From the point of creation, especially from the human standpoint, we can say that the Divine is the Absolute of all that we seek and hope and aspire for. This is not an anthropomorphic view as it may seem at a hasty glance. Anthropomorphism is to see the Divine in our own image. Thus we tend to erect a god of justice or a god of love but the idea of justice and love are exactly as our own. The god of justice would punish those who detract him whereas the god of love would favour those who love or please him. Naturally, such a divine is a projection of our own imperfections. On the other hand, the Divine is what we are not yet but would very much aspire to be. When we look at it this way then we shall see that human aspiration has itself progressed over the ages and therefore we can easily say that as we advance and progress we have higher and higher revelations of the Divine. Yet in a general way He is the absolute of all the perfection that we seek, all the beauty and bliss we aspire for, all the knowledge that we would wish to acquire, all the peace we would want to possess, all the love for which we are athirst and all these things not in their present imperfect way as we experience them but in their perfection and in complete harmony with each other. Seen thus we can look upon Him as anantaguna, One with infinite qualities, each in its purest and perfect form and attribute.
But equally, if we look at what supports the play of these infinite qualities, this march of civilisations, this human journey then we shall see behind everything, from the atomic subspaces to the vast silent space upholding the drift of galaxies, from the gaps between neuronal leaps to the moment of transition between the ingoing and the outgoing breath, from the pauses between thought to the momentary stillness between the waves of feelings and desires, a mighty all-pervading silence and stillness that supports all this manifold play but is none of these. Seen thus we may say that the Divine is void of all qualities, nirgunabrahman. Or we may combine the two as two different modes or poise of the one and same Reality and call it nirgunoguni. The ancient yogis however not satisfied with this went one more step further and posited a Non-Being beyond the Being, an Absolute beyond all relativities, a Truth of which nothing can be said, neither It is nor It is not since both are conceptions of the Mind. We are then faced with an Unknowable, Unknowable to the mind but knowable by identity and through soul experience and identity since we are That and all have emerged from That and all is in fact That.
In other words when we look at it from the other side then we can simply say that there is nothing else but the Divine. This however does not solve the riddle of creation which can only be understood if we look at it in terms of the Unmanifest Divine Consciousness of which nothing can be said and the Manifest wherein we have all the various conceptions and experiences of the Divine and his progressive unfolding through creation.
But what is the Origin of THAT of which nothing can be said? Well regardless of whether we call IT a shunyam or God or Divine or Nothing the question would still stand. The only way that this can be answered is that whatever He or She or That is, IT is Infinite and hence cannot have a birth. This technically answers it. Infinity cannot be born, It can exist as a valid conception. Only the finite is born so we can say that the Divine is infinite and hence He is ever unborn, self-existent and is also ever born into new forms. The Akshara and kshara of the Gita. But since He is also infinite qualities, infinite Knowledge, infinite Consciousness, Infinite Bliss and is self-aware He or she is a Being, the Supreme, Purushottama.
This is as far as we can go with the intellect. For the rest as we say one has to identify and discover and become the Divine to know with final certainty. This is understandable since the Divine being both superior and anterior to the Mind. This is what all spiritual experience affirms that finally one can know the Divine or whatever else the Source is by becoming That. This possibility is what yoga envisages except that the Divine being Infinite, though One, can be approached from many sides and our experience of Him or That will also differ depending upon the route and the approach. As Sri Aurobindo puts it comprehensively:
In the deep there is a greater deep, in the heights a greater height. Sooner shall man arrive at the borders of infinity than at the fulness of his own being. For that being is infinity, is God – I aspire to infinite force, infinite knowledge, infinite bliss.
Can I attain it? Yes, but the nature of infinity is that it has no end. Say not therefore that I attain it. I become it. Only so can man attain God by becoming God.
But before attaining he can enter into relations with him. To enter into relations with God is Yoga, the highest rapture & the noblest utility. There are relations within the compass of the humanity we have developed. These are called prayer, worship, adoration, sacrifice, thought, faith, science, philosophy. There are other relations beyond our developed capacity, but within the compass of the humanity we have yet to develop. Those are the relations that are attained by the various practices we usually call Yoga.
We may not know him as God, we may know him as Nature, our Higher Self, Infinity, some ineffable goal. It was so that Buddha approached Him; so approaches him the rigid Adwaitin. He is accessible even to the Atheist. To the materialist He disguises Himself in matter. For the Nihilist he waits ambushed in the bosom of Annihilation. ये यथा मां प्रपद्यन्ते तांस्तथैव भजाम्यहम्|
Also, ye yatha mam prapadyante tasyathaiva bhajamhyaham (As men approach me in whatsoever faith so do I receive them), as it is said in the Gita.