He didn't "progress" Sanatana Dharma, he corrupted it. He is responsible for one of the major corruptions. This Advaita Vedanta isn't much different than Buddhism, it's the same anti-life doctrine: everything is an illusion, nothing matters, all you do is meditate on your supposed "greater" self and ignore the world and just attain eternal bliss. I've simplified it, but that's essentially what it teaches.
Any religion that wants you to destroy your self (and by that I mean your personal self most people know it), regard it as "evil" or subjugate it to something "greater" is corrupted.
Is the idea that one's core identity is the one that experiences and not the reactions to the experiences exclusive to Advaitha Vedanta? I always thought that was a solid teaching and I've seen it repeated here, before.
Is the idea that one's core identity is the one that experiences and not the reactions to the experiences exclusive to Advaitha Vedanta? I always thought that was a solid teaching and I've seen it repeated here, before.
It isn't exclusive. What's exclusive to Advaita Vedanta is the teaching that the entire world (both material and mental) is an illusion and it doesn't matter. That's why they are derogatorily called Mayavadins by other Hindus, maya means illusion in Sanskrit.