Brahman is considered the all-pervading consciousness which is the basis of all the animate and inanimate entities and material.+

Rig Veda: ~ 'Prajnanam Brahma'- Consciousness is the ultimate reality or Brahman or God in truth.

God in truth is the Atman, the Self. Atman is present in the form of consciousness.

Do not accept any other God other than Atman not worship other than Atman.

Let these words be inscribed in your subconscious.

Nothing is real but God. Nothing Matters but love for God in truth. God in truth is everywhere and in everything.

God in truth is hidden by the illusory universe. God in truth alone is and all else is an illusion.

In  Bhagavad, Gita Krishna says: ~It is only one amongst thousands of people who strive for spiritual salvation. Even amongst such seekers, it is only the rare person who gets to know “self” correctly.’ (7.3)

In Manduka Upanishad:~   Brahman and Atman are defined as the same.

Manduka Upanishad, verse-2:~ All indeed is, this Brahman; This Atman is Brahman; He, this Atman has four steps/quarters.

While Brahman lies behind the sum total of the objective universe, some human minds boggle at any attempt to explain it with only the tools provided by reason. Brahman is beyond the senses, beyond the mind, beyond intelligence, beyond imagination. Indeed, the highest idea is that Brahman is beyond both existence and non-existence, transcending and including time, causation, and space, and thus can never be known in the same material sense as one traditionally 'understands' a given concept or object.

Imagine a person who is blind from birth and has not seen anything. Is it possible for us to explain to him the meaning of the color red? Is any amount of thinking or reasoning on his part ever going to make him understand the sensation of the color red? In a similar fashion, the idea of Brahman cannot be explained or understood through material reasoning or any form of human communication. Brahman is like the color red; those who can sense it cannot explain or argue with those who have never sensed it.

Bhagavad Gita:~ Brahman is considered the all-pervading consciousness which is the basis of all the animate and inanimate entities and material. (brahmano hi pratisthaham, ( 14.27)

Consciousness is the ultimate truth or Brahman. The consciousness alone is real. The universe is unreal. Everything other than consciousness is unreal.

The waking objects fall into two categories- practical life within the practical world, and the waking objects become unreal on the dawn of nondual wisdom. The egocentric knowledge within practical life is not Self-knowledge.  Self-knowledge means the knowledge of the soul, which is the innermost self.   The Soul, the Self, is present in the form of  consciousness.  

Thus,  basing the reason on the Soul, the Self is soul-centric the inquiry leads to nondual Self-awareness.

The waking objects exist even before they are known. They are the product of ignorance.  Thus,  they are covered by ignorance. When this ignorance is removed through wisdom then the duality ceases. 

Ignorance covers pure consciousness, which is the innermost self, limited by the object. The object itself is not self-luminous and so no covering is necessary for it to remain unknown. 

The consciousness limited by the object is self-luminous and so it remains unknown only because of the covering of ignorance. When the covering is removed through wisdom, then the consciousness underlying the object illumines the object and then the object becomes conscious. :~Santthosh Kumaar