All the Advaitic teachings of different Gurus are based on dualistic perspective.+

All the Advaitic teachings of different Gurus are based on the dualistic perspective. Orthodox Advaita is based on a religious perspective.   Thus, they will not transport the seeker to the ultimate end of understanding. The seeker has to do his own homework to realize the truth beyond form, time, and space.

Sage Sankara' gave religious, ritual, or dogmatic instruction to the mass,  but pure philosophy only to the few who could rise to it. Hence, the interpretation of his writings by commentators is often confusing because they mix up the two viewpoints. Thus,  they may assert that ritual is a means of realizing Brahman, which is absurd. 

The orthodoxy Advaita addressed the ordinary man, who finds security in the idea of causality and thus in the idea of God.

Those of superior intelligence, have no need for this idea of divine causality, and can, therefore, dispense with Sruti and arrive at the truth of Non-Dualism by pure reason. 

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 direct realization will do that. Realize yourself, turning your attention inward. :~ Tripura Rahasya, 18: 89

That is why Sage Sankara says:~ 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 perverted arguments.

Without Sage Sankara there is no Advaita (non-duality). Since it was mixed up with orthodoxy there is a lot of confusion. Sage Sankara’s quotes (selected verified) are quoted in my blogs and postings to show what Sage Sankara meant and ‘what is blocking the seekers from realizing the ultimate truth or Brahman. There are so many non-dualistic masters of the east and also from the west who expound Advaitic or non-dualistic knowledge, but none of them, are helpful to reach the ultimate end.

The ultimate truth has to be ascertained without the scriptures by realizing the self is neither the waking entity not the dream entity, but the self is the formless Soul, which is present in the form of consciousness. In the realm of truth the form, time, and space are created out of single stuff. That single stuff is consciousness. Realizing the single stuff as the ultimate truth is Self-realization or truth realization. To realize this truth, there is no need for scriptures. 

The ultimate truth has to be realized first, then only it is possible to know what the scriptures are saying.

Scriptures are being added from time to time. This process will go on. There is the final authority among them? One contradicts the other: duality reigns supreme. : ~ Santthosh Kumaar