The spiritual realm of ancient India has many layers, abstractions and contradictions. The meditation and ruminations over our epics tend to produce many philosophers who surprisingly asked original questions. On the other hand, the Abrahamic religions more or less “dictates” than being a fertile crescent for various ideologies. Abrahamic religions gave rise to many religious monastic orders, which tends to address the aspects pertaining to the order, structure, tenets of the religion, without any appeal to a generic philosophy what so ever. More emphasis is placed on fastidious following of the respective order, rather than encouraging any outward directed original debates. That approach is presumptuous at the best in the sense that, the measure of the quality of an adherent is presumably the degree of his devotion to the respective monastic order. It provides more answers than questions.
Despite being much mythological, Indian philosophers propounded the idea of Adwaita, a surprisingly original mind/matter problem albeit expressed in Indianspeak. Spiritual gurus like Osho, UG, Ramana Maharshi were original philosophers. I first came to know about Ramana Maharshi from one of my professors Phd dissertation's dedication page. His teaching is a form of Advaita stripped of its complex obfuscated shell. He simply asks where does the feeling of “I” emanate from? It helps to ask the question “Who am I?” continuously. “I” is latched on to multiple things. Once “I” gets unlatched from its attachments/features/attributes, “I” fades away. Every time when one chant “I” deeply, he goes deep into his self. Then suddenly “I” is not there. All you find is a vague, formless, attributeless, unexplainable, transcendent self. Your mind stare at something which is not attached to anything you can identify. That unexplainable self is “I”. Mind as we experience is the self associated with something. Pure self is quality less. Once we tries to reach to the pure self, that self dissolves away. And that self is a part of transcendent oneness.
Its a form of Advaita, but in a more accessible form. And it is independent of religion. To me, it’s genuinely spiritual. Maybe a more scientific explanation to the experience of self is ones subjective experience of stray and random electrical impulses in the brain, when one tries to free his mind of any thoughts. Disregarding the true underlying causes of experiencing “I” through a simple mechanism, It kinda tried to connect thoughts arising from the materialistic brain to some transcendent non-materialistic oneness. Pretty profound attempt by a sadhu. If through your religious dogmas you appeal to a transcendental entity, who you think lies outside the existing bounds of perceivable reality, then you are spiritual of the highest order.