In reality, there is no duality, no differentiation. Only Atman exists.+

Brihadaranyaka Upanishad says: ~  In that unitive state there is neither father nor mother, neither worlds nor gods nor even the Scriptures. In that state, there is neither thief nor slayer, neither low caste nor high, neither monk nor ascetic. The Self is beyond good and evil, beyond all the suffering of the Human Heart

Sage Sankara says:~ Atman is Brahman.   The Atman alone is real. He has declared this Advaitic truth, which is the ultimate truth to the whole world, many centuries back.

Thus, the Atman which is present in the form of the consciousness is real and eternal, the world in which we exist is merely an illusion. 

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

When Bhagavad Gita says, God is considered the all-pervading consciousness which is the basis of all the animate and inanimate entities and material then nothing has to be accepted as God other than consciousness. 

Lord Krishna says Ch ~V: ~ “Those who know the Self in truth.". The last two words (tattvataha) are usually ignored by pundits, but they make all the difference between the ordinary concept of God and the truth about God.

The dualistic worship of "God” is only for the ignorant populace. The God in truth is only Atman, the innermost Self.   In reality,  there is no duality, no differentiation. Only Atman exists. 

The Vedas confirm God is Atman (Spirit), the Self.

Rig Veda: ~ The Atman is the cause; Atman is the support of all that exists in this universe. May ye never turn away from the Atman, the  Self. May ye never accept another God in place of the Atman nor worship other than the Atman?" (10:48, 5)

How can you worship God? That implies two ~ the worshipper and the worshipped, whereas God is nondual. One can worship his idea of God only or realize his unity with it when he can’t worship it as apart.

When Upanishads and Vedas declare that, “God is in the form of the Athma, and God is indeed Athma itself” then why accept another God in place of the Atman or worship other than the Atman. 

That God created the world is an absolute lie; nevertheless, you will find Sage  Sankara (in his commentary on Vedanta Sutras) clearly says this! He has to adapt his teachings to his audience, reserving the highest for philosophical minds.

The Brahma Sutras are based on religion and dogmatism, but in the commentary, Sage  Sankara geniusly introduced some philosophy.

 If it is objected that a number of Upanishads are equally dogmatic because they also begin by assuming Brahman, but a few Upanishads do not but prove Brahman at the end of a train of proof.

The causality and creation, but these are for religious people only.  Religion is only for those who are unable to understand truth beyond form, time, and space. Religion is not final. It only gives satisfaction to the populace. The Self - knowledge is for the whole of humanity to free them from experiencing birth, life, death, and the world as reality.

People of small intelligence follow religion and believe that the world was created by God. But how do they know that He did so? When a pot is created, one can see both pot and its maker, but not in the case of the world.

Self-knowledge or Brahma Gnana or Atma Gnana is meant only for those who have an intense urge, and courage to accept the truth with humility and reject the untruth. Since people start comparing their scriptural knowledge, it becomes impossible to assimilate and realize the Advaitic truth.   Therefore, there is no need to convince anyone other than our own selves to get a firm conviction.

Mundaka Upanishad condemns rituals.  The Para or Higher knowledge is the knowledge of the Supreme Being while the Apara or Lower Knowledge is that of following sacrificial rites and ceremonies. (1/2/ 1 – 6)

The identity of Atman and Brahman is a matter of absolute truth, not just a temporary ritual identification.

Sage Sankara’s wisdom is nothing to do with the orthodox belief systems. Some philosophers in the past dissented from this interpretation of Vedanta philosophy, holding that the incarnated Souls were separate from the Divine Essence and only finally merged with it after the cycles of birth. 

All Gurus and paramparas belong to the orthodoxy. Orthodoxy is nothing to do with  Sage Sankara’s Advaitic wisdom.

Identifying the Atman as Self is the most important in the Atmic path.  Consciousness is the substratum on which the dualistic illusion is experienced. Consciousness is hidden by the dualistic illusion.   The consciousness that dwells in everything and everywhere in the universe, is the dualistic illusion.

The innermost Atman, the real Self. Atman is present in the form of consciousness. The whole dualistic illusion is nothing but consciousness,  consciousness alone is real and eternal. All these are meant for the ignorant populace.

Genuine philosophy must be independent of religion, that in Sage Sankara himself the Saguna Brahman or a personal God is only a part of the phenomenal (if not illusory) world, and the Nirguna Brahman (God in truth) is the only reality and has nothing to do with religion.  

Sage Sankara’s Supreme Brahman (God in truth) is impersonal, Nirguna (without Gunas or attributes), Nirakara (formless), Nirvisesha (without special characteristics), immutable, eternal, and Akarta (non-agent).

Brahman is above all needs and desires.

Brahman is always the Witnessing Subject.

Brahman can never become an object as it is beyond the reach of the senses.

Brahman is non-dual, one without a second.

Brahman has no other besides it.

Brahman is destitute of difference, either external or internal.

Brahman cannot be described because the description implies a distinction.

Brahman cannot be distinguished from any other than It.

In Brahman, there is not a distinction between substance and attribute. Sat-Chit-Ananda constitutes the very essence or Svarupa of Brahman, and not just Its attributes.

The Nirguna Brahman of Sage Sankara is impersonal. Sage Sankara: ~"That which permeates all, which nothing transcends and which, like the universal space around us, fills everything completely from within and without, that Supreme non-dual Brahman  (Godin truth) ~ that thou art."

Sage Sankara, Upanishads, and Vedas declare that “God is in the form of the Athma, and God is indeed Athma itself” then why accept another God in place of the Atman nor worship other than the Atman.

Sage Sankara says: ~ Atman is Brahman. The Atman alone is real and eternal and it is not religious truth.  Sage Sankara declared this Advaitic truth, which is the ultimate truth to the whole world, many centuries back is the rational truth, the scientific truth, and the ultimate truth.

Thus, the Atman which is present in the form of consciousness is real and eternal, the world in which we exist is merely an illusion.:~Santthosh Kumaar