The strongest difference between Vedanta and Buddhism is that emptiness applies to everything. Vedanta typically teaches that emptiness only applies at the level of Maya, and that Brahman is not empty. Keep in mind we are comparing the systems from a conceptual viewpoint, and conceptually, they are quite different. I have never heard of a Buddhist teacher, Kagyu or not, who posited a single, universal consciousness that intentionally forgets itself and arises as numberless beings.
Not really, since some Christian and Muslim mystic actually apply emptiness to God/Brahman. The difference between Theravadan emptiness and Christian and Muslim mystic emptiness is that in Theravada emptiness is cause by continuously changing reality; therefore, we have conventional truth (nothing is changing to our eyes) and ultimate truth (nothing actually states the same the outer world and the inner world). While Christian and Muslim mystics refer to the emptiness as non-changing which is cause by tripping the materialistic view.
So Theravadas would argue that since the emptiness is not really eternal infinite metaphysical substance, but the emptiness is caused by continuously changing reality (inner and outer world), so even if the God/Brahman is referred to as emptiness by the mystics then Theravadins would argue against God/Brahman on the bases of that eternal infinite metaphysical substance cannot exist because of continuously changing reality (inner and outer world).
Both sides of the two truths show significant differences, and the unity of the two is very much an exclusively Buddhist view. Buddha-nature is not simply some ultimate awareness, but it refers to the buddha qualities, the buddha bodies, and the buddha knowledges/wisdoms. For the Advaitins liberation means the end of all transitory appearances, similarly to the Samkhya teaching where Prakrti completely stops, and only the ultimate remains that practically does nothing apart from being absorbed in itself. So, the Buddhist view is that the ultimate is essentially empty and functionally active, while the Hindu one is that the ultimate is essentially substantial and functionally inactive.
In Hinduism, Christianity, Islam, etc., "the theistic enlightenment" has also qualities such as enlightened knowledges/wisdoms, enlightened bodies and enlightened qualities. Hindu, Christian and Muslim mystics (which I have read) would describe enlightened people as people with enlightened bodies. Their bodies would be described always as pure light and source of light; therefore, their bodies would be Levitating a little bit above the ground, etc. etc.
The same with enlightened knowledges/wisdoms, Hindu, Christian and Muslim mystics described this knowledge as "ability to see the future past of one's life and others people lives". Therefore, this argument is also a bad argument.
Theravadins would argue that even though these people have enlightened knowledge/wisdom, enlightened bodies and enlightened qualities, these qualities are caused by "temporary" enlightenment because they have "wrong view" which is that there is no God/Brahman so they are not ultimately free from attachments which is attachment to God/Brahman.
But I wonder, Wayfarer - and by that I mean, I don't really know - if that notion of existence couldn't also apply to Atman/Brahman? Perhaps not unilaterally, but in certain contexts depending on which philosophical iteration one is dealing with. If so, it doesn't really get us out of the problematic. One naturally thinks of that old Upanishadic refrain "neti, neti" which clearly implies that one can only arrive at Atman via negation, which in the same breath, problematises the sense that Buddhists often have, of some kind of Vedantic reification of (ideal) existence, tangible Being, etc.
Good point. Hindu, Christian and Muslim mystics would always negate God/Brahman. This is kinda the reason why it is so difficult to argue this since it was supposed to take one post, with similarities and differences, but there are now over 100 replies. where some post like the ones I have quoted are just stupid and ignorance about Hindu, Christian and Muslim mysticism.
Also to the admins, in this post as you can see I am not comparing Tibetan Buddhism to anything, I am just simply quoting assumptions about Advaita which are simply wrong, and arguing as Theravadin against the correct version of Advaita arguments.