Without knowing the difference between religion and spirituality (Adyathma) it is very difficult for the seeker to grasp the Advaitic truth.+

Adyatma is nothing to do with religious sects or creeds and religious beliefs or any philosophy or any thinkers' teachings. Adyatma is pure spirituality. Knowledge of Atma is Adyatma. Advaita is Adyatma. 

Adyatma is the knowledge of the truth beyond form, time, and space. Bifurcate religion, yoga, and theoretical philosophy and base the truth on the Athma it is Adyathma.

Adyatma is based on the ultimate truth which is based on the Atman or Spirit, which is the Self.

Sage Sankara's Advaitic wisdom is pure spirituality or Adyathma.

Advaitic wisdom of Sage Sankara is pure spirituality or Adyathma do not make it a philosophic sect. Sage Sankara’s path of wisdom is the independent search for truth.

Sage Sankara’s Advaitic wisdom deals with the practical bearing of philosophy to remove initial prejudice that it is remote from life. 

Some scriptures have presented fragments of truth imbedded in the covering of stories, histories, and picturesque touches of mysticism.

The seeker should not mix religion, mysticism, and yoga with the path of wisdom. All the Gurus of the east and west touch on mysticism to make it more attractive to feed the crowd. 

It is necessary to reach larger numbers of serious seekers who care for truth alone. Philosophy has to deal with the ultimate truth, not mere words, not this Guru's or that Guru's interpretation. All the interpretation of different scriptural scholars is an arena of conflicting interpretations.

All the gurus of the east and west interpreting Advaita from a dualistic standpoint or orthodox point of view and they are still dealing with words, not truth.  It proves that they have not understood the Advaitic wisdom of Sage Sankara.

Remember:~

Without knowing the difference between religion and spirituality (Adyathma) it is very difficult for the seeker to grasp the Advaitic truth.

If one religious scholar quotes his religious scriptures as an authority as final, the other scholars from other religions do not agree because he feels his religious scriptures are superior and final.

Thus, if Jesus says so, reply that Lord Krishna says the opposite! If a man quotes Bhagavan Buddha in proof, others may quote Mahavira in disagreement. This may eventually show the man that no person can be a final authority.

Tripura Rahasya: ~ Second-hand knowledge of the Self-gathered from books or Gurus can never emancipate a man until its truth is rightly investigated and applied; only the direct realization will do that. Realize yourself, turning the mind inward. (18: 89)

Remember:~

All your accumulated knowledge from different Gurus and teaching is nothing to do with Advaitic wisdom or Self-knowledge or Brahma Gnana or Atma Gnana. All your accumulated knowledge is not of any use in realizing the ‘Self’, which is hidden by the illusory form, time, and space. If you want to realize the ‘Self’ then you have to drop all accumulated knowledge and start afresh. Do not hold your accumulated knowledge as a yardstick.

Mundaka Upanishads: ~ ‘So-called spiritual pundits and learned are called children because a child takes whatever it thinks as truth. The question never occurs to children “Is what I have seen or thought really the truth?" (P.334 line 9)

The scriptures are for ignorant masses, who wholly accept the material world as it presents itself. Non-dualistic or Advaitic wisdom is for those who have begun to realize that things are not what they seem.

Even the Upanishads are Self-contradictory. Pundits and scholars give conflicting interpretations of them. When one uses his own Common-sense he becomes aware that, the final authority, therefore, is using his own reason. One should apply his reason to the scriptures before accepting them as truth.

Ashtavakra: ~ “My child you may speak upon various scriptures or hear the sermons on the scriptures. But you cannot establish in the ‘Self’ unless you forget all. 16-1 – p49.:~Santthosh Kumaar