First of all, “nonduality” is the same as “monism” in metaphysics, so “mystical monism” is an accurate label for your view. There could be lots of equivalent labels, but that’s one of them. In metaphysics “monism” means “any of various theories holding that there is only one basic substance or principle as the ground of reality, or that reality consists of a single element.” So no, it doesn’t have to be a substance. You think a single consciousness is at the bottom of everything. That’s a principle, if not a substance.
Second, you don’t think I can derive the impression of that mystical monism (or of whatever you want to call it) from my philosophical perspective that combines naturalism, existentialism, pantheism, neo-Kantian, pragmatic epistemology, and so on? Of course I can. That’s why our viewpoints are alternatives. You have your way of talking about philosophy, religion, history, and so on, and I have mine.
You can say mine is a subset of yours, if you like, but that’s just an uncharitable way of stamping your feet and saying that you think your viewpoint is correct, that it encompasses everything else. I could assert the very same thing about mine: my philosophy encompasses yours since I could derive the subjective impression of oneness from naturalism, pantheism, pragmatism, etc. Instead, I say charitably and humbly—and in line with the humanistic sense of fallibility and with late-modern irony—that our views are alternatives. I say, “live and let live,” and I don’t go around harassing and personally attacking you on this platform.
And you don’t think you have a “worldview”? That’s just a semantic game. The labels don’t matter. The concepts of mystical monism (or of whatever you want to call your sort of enlightenment) amount to a way of talking about the world that excludes other ways. You think that existentialism, for example, is false if this sort of philosophy posits absurdity in life. There’s no real absurdity but only the illusion of it, according to you. But that very emphasis on something as “real,” and the de-emphasis on something else as “illusion” testify to your worldview. You make judgments about what’s true or sensible, and those judgments differ from other people’s judgments.
Indeed, you claim to know yourself since you claim to identify with the consciousness that underlies everything in the universe. But I’m not seeing the humility you’re supposed to expect from that supposed self-understanding. You can’t even grant others the right to their perspectives. You think your worldview swallows up all others in totalitarian fashion, which licenses these harassments. I suppose that identifying with divine consciousness might generate the opposite of humility, but that too would distinguish your worldview since it would mean that mystical monism evidently has ethical consequences that differ from the ethics of rival worldviews.