Sage Sankara proved the existence of God on the Vedic perspective and also proved the existence of God rationally.+

The word Brahman means ultimate truth or reality which cannot be indicated by any word. The Brahman can be expressed through silence because it is beyond the experience of form, time, and space. Therefore, the word Brahman clearly stands for the essence of the three states, which is consciousness only.  

Self-knowledge or Brahma Gnana or Atma Gnana is for realizing the Soul is the Self. The Soul is present in the form of consciousness.

Sage Sankara disagrees with Buddhists who say, there is nothing - nonentity. Sage Sri, Sankara believes there is some reality, even though things are not what they appear to be. If one knows the truth, he will know what to do to find inspiration for action. The seeker of truth‘s subject is to know what is real and what is unreal.

Buddhism says:~ ‘All things are illusory and nothing exists. However, Advaita avers that it is not so. It says that the universe, of course, is illusory, but there is Brahman (consciousness), that exists, forming the very substratum of all things (illusion or universe).

Sage Sankara opposed the Buddhists only, who misunderstood Buddha and became atheists. According to Sage Sankara, meditation always means the critical analysis about the Self to get salvation from worldly tensions. Due to the eccentric ego of the then atheists, Sage Sankara did not go beyond this since the atheists will not accept God beyond themselves. This limitation is not due to limited knowledge of Sage Sankara but is due to the existing situation of the psychology of the surrounding society.

Even Bhagavan Buddha kept silent about God because the society dealt by Him consisted of Purvamimamsakas, who were strong atheists. Bhagavan Buddha said that everything including the Self is only relatively real (Sunya). This is correct because the Self is a part of the universe, which is relatively real with respect to the absolute unimaginable God. The Bhagavan Buddha stopped at this point because the atheists cannot realize the existence of an unimaginable God indicated through His silence.

The point of Bhagavan Buddha is that if God is non-existent, the entire creation including the Soul, the ‘Self ‘is non-existent.

How the universe can exist without the Soul because the universe is merely an illusion created out of the Soul.

The Atman is self-evident. It is not established by extraneous proofs. It is not possible to deny the Atman because It is the very essence of the one who denies It. The Atman is the basis of all kinds of knowledge, presuppositions, and proofs.

The Soul is present in the form of consciousness and is real and eternal. The world in which we exist is an illusion created out of consciousness.

Atman is Brahman (God), the One without A Second.  

Remember:~ 

According to Vedas and Upanishads, God is Athma: ~

Rig Veda: ~ The Atman (Soul or Spirit) 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)

Brihadaranyaka Upanishad: ~ Brahman (God in truth) is in the form of the Athma, and it is indeed Athma itself’.

 
Sage Sankara’s Supreme Brahman (God) is impersonal, Nirguna (without Gunas or attributes), Nirakara (formless), Nirvisesha (without special characteristics), immutable, eternal, and Akarta (non-agent). It is above all needs and desires. It is always the Witnessing Subject. It can never become an object as it is beyond the reach of the senses. Brahman is non-dual, one without a second. It has no other besides it. It 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.

Thus, it refers to a formless and attributeless God that is the Atman (Soul), the innermost ‘Self’ within the false experience. Thus, it indicates clearly all the Gods with form and attributes are mere imaginations based on the false self.  Atman or Soul, the ‘Self’ is God in truth.

Sage Sankara wanted to establish the existence of the Brahman. For this purpose, He made the Atman as the Brahman. He brought out the identity of Self with the consciousness and made the Atman the Brahman. Since one will not negate the existence of his Self, he will accept the existence of the Brahman, which is the Atman or Soul, the Self. Both Bhagavan Buddha and Sage Sankara kept silent about the absolutely unimaginable God. The same philosophy was dealt with by them from different angles in different situations.

Sage Sankara proved the existence of God from the Vedic perspective and also proved the existence of God rationally.

Sage  Sankara himself had often said that his philosophy was based on Shruti, or revealed scripture. This may be, because,  Sage Sankara addressed the ordinary man, who finds security in the idea of causality and thus, in the idea of God—and Revelation is indispensable to prove the latter. He believed that those of superior intelligence, have no need of this idea of divine causality, and can, therefore, dispense with Shruti and arrive at the truth of Non-Dualism by pure reason.: ~ Santthosh Kumaar