Self-Knowledge or Brahma Gnana or Atma Gnana is necessary to realize the ultimate truth or Brahman

Simply repeating or reading or hearing what scriptures say or whatever god men or guru says does not make one a Gnani. Seeker should not accept anything as truth without verification. 

Buddhism says: all things are illusory and noting exists.  However, Advaita avers that it is not so.  It says that the universe of course is illusory, but there is Brahman, that exists forming the very substratum of all things.

 

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.

 

The Self –knowledge or Brahma Gnana or Atma Gnana  is goal of the true seeker.  Self-knowledge is end of all egocentric knowledge.

Self-knowledge or Brahma Gnana or Atma Gnana is declared by the Indian sages in the past has to be mentally excavated from labyrinths of philosophy. So many conceptual divisions invented by teachers of philosophy by their excessive analysis and different idea of truth and interpretations. All these concepts and ideas are never ending process. 

The seeker of truth need not take the path of doubt and confusion, which takes him nowhere.  Fortunate is the seeker who does not lose himself in the labyrinths of these theoretical philosophies.  By perfect understanding of ‘what is what’ leads to non-dual self-awareness. Seeker has to behave in a   normal and sane way and silently reflect on the subject constantly.

Even biblical insights say the god(truth) is within:-

Luke 17

20 And when he was demanded of the Pharisees, when the kingdom of God should come, he answered them and said, "The kingdom of God cometh not with observation: Neither shall they say, 'Lo here! or, lo there!' for, behold, the kingdom of God is within you."

This means that the "kingdom of God" (heaven) is within - it is not a place to be reached, rather the truth of one’s true existence, which is beyond form, time and space. 

The formless soul or consciousness is the innermost self   and it is the cause of the form, time and space and it itself is uncaused. Thus soul or spirit is the ultimate truth or Brahman or Christ or Buddha’s nature.    

Corinthians 3:17:  Now the Lord is the Spirit, and where the Spirit of the Lord is, there is freedom.

 According to the New Testament, Jesus said to his disciples: ‘To you it has been given to know the secrets of the kingdom of God; but for others they are in parables, so that seeing they may not see, and hearing they may not understand’ (Luke, 8:10). While speaking to the multitude in a veiled manner, ‘privately to his own disciples he explained everything’ (Mark, 4:34), and advised them not to ‘throw your pearls before swine’ (Matthew, 7:6).

Therefore Self-Knowledge or Brahma Gnana or Atma Gnana is necessary to realize the ultimate truth or Brahman. Self –Knowledge or Brahma Gnana it is only for those who has intense urge to know the ultimate truth or Brahman or Inner Buddha or Christ.