Sage Sri Sankara clearly indicated that: - yoga, intellectualism, scriptural mastery is not the means to Self-Knowledge or Brahma Gnana or Atma Gnana. But by the realization of one's identity with consciousness, which is ultimate truth or Brahman, freedom from experiencing the illusion as reality is possible, and by no other means.
The seeker of truth has to get rid of his doubts through deeper inquiry, analysis and reasoning on his own, to realize the fact that, the self is not the form but self is formless. Thus his analysis and reasoning has to be based on the formless not on the form. By simply go on believing and accepting whatever said by the punditry and intellectuals will not lead one towards path of wisdom. All the doubt has to be got rid of "by the sword of Self - Knowledge or Brahma Gnana or Atma Gnana." The scriptures, yoga are not necessary if one follows the inner (formless) path. Religion and yoga are not the means to path of wisdom.
Sage Sri , Sanakara said:-
[VC]65. As a treasure hidden underground requires (for its extraction) competent instruction, excavation, the removal of stones and other such things lying above it and (finally) grasping, but never comes out by being (merely) called out by name, so the transparent Truth of the self, which is hidden by Maya and its effects, is to be attained through the instructions of a knower of Brahman, followed by reflection, meditation and so forth, but not through arguments.
One cannot expect mental spoon feeding for everything. The Seeker has to do his own homework. One will not understand it through argument, which leads nowhere but to perversity.
BUDDHA SAID: - Believe nothing just because a so-called wise person said it. Believe nothing just because a belief is generally held. Believe nothing just because it is said in ancient books. Believe nothing just because it is said to be of divine origin. Believe nothing just because someone else believes it. Believe only what you yourself test and judge to be true.
Swami Vivekananda said: - “You have to grow from the inside out. None can teach you, none can make you spiritual. There is no other teacher but your own soul.”
It is for the seeker to mentally excavate by deeper self-search and realize what is truth and what is untruth and accept only un-contradictable truth. Truth is not some theory or teaching but it has to be ascertained by the seeker himself.
Universe exists only when the mind exists. The universe ceases to exist without the mind (I). When there is no mind there is no universe. In deep sleep there is no mind therefore there is no universe. Therefore mind itself is universe the universe appears as waking or dream. The waking experience is parallel dream and dream is parallel waking experience.
The formless substance and witness of the waking or dream or universe is Atman, which is in the form of consciousness. The formless substance and witness are one is essence that essence is Atman (soul or consciousness). Thus Atman is Brahman that is consciousness is ultimate truth. Thus on the standpoint of Atman the universe (mind or 'I') is mere illusion.
That is why Sage Sri Sankara quoted:-
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.
Upanishads:- They alone in this world are endowed with the highest wisdom who are firm in their conviction of the sameness and birthlessness of Atman. The ordinary man does not understand their way ( Chapter IV — Alatasanti Prakarana 95-P-188 in Upanishads by Nikilanada)
When serious seeker reaches a stage with all his baggage of accumulate knowledge, then uncertainty haunts him. Whether he is right?" Where is the certainty that he is proceeding on right lines?" Thus doubts arise and the inquiring spirit comes and impels to search elsewhere for truth where it will not be possible even to have doubt. The test is therefore in experience. And only in non-duality, where there are no two to argue about views or to have difference of opinion can such doubtlessness be possible. Belief depends upon unstable bases whereas certainty depends on proof.