Ultimate truth is based on the soul therefore whatever practiced on the base waking entity will not yield any fruit, because the waking entity is the false self within the false experience.

 One should not  try to judge  ultimate truth holding religious or yogic doctrine as a yardstick.  Religion and yoga is not the yardstick to judge the ultimate truth   because they are practiced on the base of waking entity or physical self or ego.   The waking entity or physical self or ego is false self within the false experience (waking).    The non-dual truth has to be viewed and judged without scriptures, and on the base of the soul, the innermost self.  This formless path is inner path is without the religion or scriptures or god or yoga. The formless path is pathless path is without guru and self – treading towards direct realization.

Ultimate truth is based on the soul therefore whatever practiced on the base waking entity will not yield any fruit,   because the waking entity is the false self within the false experience. The religion and yoga are based on the form therefore they are   based on the matter (form) whereas the spirituality is based on the spirit (formless).  Thus religion and yoga are not spirituality, hence there is need to bifurcate spirituality from matter (form) based religion and yoga.

Advaita refers to non- duality. Non -duality is not a theory or concept it is the nurture of the innermost self, which Atman (soul or spirit or consciousness).  Thus whatever is based on the soul is spiritual. The soul is eternal identity which has no birth, life and death, because it is the formless.  Soul, which is in the form of consciousness, is the formless substance and witness of the illusory experience of birth, life, death and world.

The religion is based on the form. Without the form there is no question of religion. The religion accepts the concept of god, and believes the body itself as self, and injects theoretical code of conduct to live in the world, whereas in spirituality, the soul or consciousness is the true self and body, ego, world, conceptual god are part of the illusion created out of consciousness. 

Swami Vivekananda:-

Creeds and sects have their parts to play, but they are for children, they last but temporarily. Books never make religions, but religions make books. We must never forget that. No book ever created God, but God inspired all the great books. And no book ever created a soul. We must never forget that. (Talk given at Unity Hall, Hartford (Connecticut), USA, on March 8, 1895, as reported in "Hartford Times" (March 11, 1895). Complete Works, 1.324.)

Non-dualistic orthodoxy is based on the form. Thus it is conduct oriented and trying to prove the truth on the base of scriptural authorities, whereas the ultimate truth is based on the soul, the innermost self.  Ultimate truth has to be proved on the base of soul-centric reasoning without the scriptures.

Orthodoxy holds the caste, religious rites, god and guru glorification, scriptural studies, virtues, good deeds and physical conducts as the means to acquire the self-knowledge, whereas in pursuit of truth, only intense urge to know the truth, receptive mind, sharpness to grasp, courage to accept the truth and reject the untruth are necessary.

The guru is needed in only in religion and yoga.  In pursuit of truth there is no need for the guru. Gnani will never accept himself as guru nor does he claim himself as a Gnani.   One who accepts himself as guru does not know the truth. When one inquires in to the nature of the mind or universe    than the truth will start revealing on its own.

That is why 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.”

The religion, concept of god and scriptures are greatest obstacle to acquire self-knowledge.  The scriptural knowledge fuels the ego. And ego makes one experience the duality as reality.  Duality makes one blind to the truth, and makes one accept, the egocentric theories based on the false self as authority. 

Buddha said:-

Do not believe a spiritual teaching just because:-

1.      It is repeatedly recited,
2. It is written in a scripture,
3. It was handed from guru to disciple,
4. Everyone around you believes it,
5. It has supernatural qualities,
6. It fits my beliefs anyway,
7. It sounds rational to me,
8. It is taught by a respectable person,
9. It was said to be the truth by the teacher,
10. One must defend it or fight for it.

However, only when it agrees with your experience and reason, and when it is conducive to the good and gain of oneself and all others, then one should accept the teachings, and live up to them." ....Buddha.

Gaudapada says that:- The merciful Veda teaches karma and Upasana to people of lower and middling intellect, while Jnana is taught to those of higher intellect.

This clearly indicates that religion, which is based on individual conduct, prescribes karma and Upaasana to people of lower and middling intellect, therefore religion is for the lower intellect. And wisdom is for those are capable of inquiring into their own existence.  

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)

If Brahman is considered the all-pervading consciousness then, it is necessary to realize, the consciousness as self, which pervades all the three states to realize the fact that there is no second thing exists other the consciousness. Thus, consciousness [Atman] is ultimate truth [Brahman]. 

 

As indicated in ISH Upanishads: - By worshipping gods and goddesses you will go after death to the world of gods and goddesses. But will that help you? The time you spend there is wasted, because if you were not there you could have spent that time moving forward towards Self-knowledge, which is your goal. In the world of gods and goddesses you cannot do that, and thus you go deeper and deeper into darkness.

It clearly indicates that:-If the human goal is to acquire Self-Knowledge then why one has to indulge in rituals and glorifying the conceptual gods and goddesses to go in to deeper darkness. Instead   spend that time moving forward towards Self-knowledge, which is one’s prime goal.   

Since it is eternal and infinite, it comprises the only truth. The goal of Vedic religion, through the various yogas, is to realize that the consciousness (Atman) is actually nothing but Brahman.

 The Vedic pantheon of gods is said, in the Vedas and Upanishads, to be only higher manifestations of Brahman. For this reason, "ekam sat" (all is one), and all is Brahman.

Thus, the goal is to realize Atman [consciousness].  If Atman [consciousness] is nothing but Brahman and by realizing Atman [consciousness] as Brahman [ultimate truth] is truth realization or Self-Realization , then there is no need to follow religion, study scripters or glorifying gods and gurus and  follow the path of doubts and confusion by losing oneself in the labyrinths of philosophy, when there is an easier path.  By mentally tracing the source of the mind from where it rises and subsides one becomes aware of the fallacy of the mind, which rises as waking or dream and subsides as deep sleep.  The mind raises form consciousness and subsides as consciousness.

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]

Therefore, if one is seeking truth he has to know his true self is not physical but is the consciousness, which is in the form of consciousness.  

Self-knowledge or Brahma Gnana or Atma Gnana  cannot be attained by study of the Vedas and intellectual understanding or by bookish knowledge.  Therefore there is no use of studying the Vedas and other scriptures in order to acquire the non-dual wisdom.  That is why Buddha rejected the scriptures, and even Sri, Sankara indicated that, the ultimate truth lies beyond religion, concept of god and scriptures. 

Thus it is necessary to follow the inner(mental)  path dropping all the accumulated baggage and move forward to reach the destination in lesser time and effort.