Knowledge of this ultimate truth is called Advaitic wisdom or Brahma Gnana or Atma Gnana.

 

When ‘Self’ is not the waking entity (body or ego) , whatever one believed of the god and world and religion, heaven and hell and theories and accepted as truth as  waking entity is bound to be falsehood. 

 Only if the ‘Self’ is waking entity  then only whatever one believed of the religion god and the world and accepted as reality has meaning and value. Therefore, whatever experienced in waking experience as reality will remain reality until all the three states are not inquired, analyzed and reasoned in to.

That is why Sri Sankara, indicated  in Bhaja Govindam says: - [Jnana Viheena Sarva Mathena Bajathi na Muktim janma Shatena] - one without knowledge does not obtain liberation even in a hundred births, no matter which religious faith he follows. 

Religion promises moksha in next world or next life whereas the moksha or nirvana is possible right now (in this very life) and right here (in this very life).  Simply repeating or reading or hearing what scriptures say or whatever god men or guru says does not make one to understand, assimilate and realize the non-dual truth. Seeker should not accept anything as truth without verification.

Truth cannot be got in external world. The truth is hidden within the three states as their formless substance and witness.  By Becoming a monk and renouncing the worldly life and running away to mountains to acquire non dual truth or Brahman is a foolish venture.

Brahman is within.  The formless soul, which is in the form of consciousness, is ultimate truth or Brahman.   The formless soul is the innermost self and it is not an entity or identity within the waking or dream, but it is the formless substance, witness and source of the three states.    Formless soul is the source of the three states, from where the mind or universe (waking or dream) erupt and subsides. 

All the confusion and doubts arise because one doesn’t know what he is seeking. He thinks “ego or waking entity” is self and he is trying to acquire self-knowledge on the base of ‘ego or waking entity’ which is false self within the false experience. He thinks truth is some thing accomplished from the external experiences. So instead of verifying it through deeper self-search he tries to regulate his human attributes through yoga and devotion and religious code of conduct and tries to acquire the self-knowledge or brahma Gnana or Atma Gnana .

 Once   three states  are analyzed  and when one becomes aware of the existence of the formless witness apart from the three states   then the truth starts revealing and he becomes aware of the fact that the waking experience is mere mirage created out of consciousness the innermost self.  therefore the waking entity is  false self within the false experience. on the standpoint of the formless witness of the three states , which is the formless soul or consciousness, the three states are  mere mirage. the formless witness of the mirage is real and eternal.  the formless witness and the mirage are one in essence.  Therefore, the formless  soul (Atman)  or consciousness    is ultimate truth or Brahman. Knowledge of this ultimate truth is  called Advaitic wisdom  or  Brahma Gnana or Atma Gnana.  

   

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

    

They alone in this world are endowed with the highest wisdom who are firm in their conviction of the sameness and birthlessness of Ataman. The ordinary man does not understand their way. [Chapter IV — Alatasanti Prakarana 95-P-188 in Upanishads by Nikilanada]

The yogi, religionists and Atheists take the physical self as reality. And, they have the conviction that the world is apart from the physical self. They think that they are an individual and separate from the world. Thus, there practice is centered on the physical self/ ego. The physical self and the world exist within the waking experience. All egocentric practice leads towards imagination and speculation hallucination.

Sri Sankara says [VC] 63. Without causing the objective universe to vanish and without knowing the truth of the Self, how is one to achieve Liberation by the mere utterance of the word Brahman ? — It would result merely in an effort of speech.

So long as one is in the realm of duality, one has to explain how or why one thing came from another; and contradictory views are expressed. But when a Gnani shows there is no second, there is no production, and the contradictions do not arise at all, when the ultimate thing is consciousness alone. Thus consciousness is ultimate truth or Brahman.

The dualist's’ arguments are based on false self [ego or waking entity] and false experience [waking or dream or universe]    to show the weakness of the position of dualistic view point.  They at their wits end to explain.

 Existent cannot be a cause and effect at the same time, from the point of view of the dualists, but deeper self-search shows the Existent is no-two and causality can’t rise at all. Dualistic theory says that whatever was in the cause was also in the effect. They say that the gold brick, the gold medal, the gold ornaments --are in the seed--the gold. Deeper self-search reveals the fact that, if cause and effect are one what is the difference between the two? 

 

Until and unless the conviction of birth, life and death and thoroughly verified through inquiry, analysis and reasoning, one is bound to believe that the world is prior to him and he is born in it and he is an individual separate from the world.  This birth, life and death conviction is firmly rooted in every individual; therefore, there is a necessary to mentally dismantle this conviction to remove the physical barricade to dross the threshold of duality.  The separation is only in duality. In realm of truth the duality is mere illusion.