A good question, and my apologies for posting without explaining!
It’s a reference to the Advaita Vedanta. The Encyclopedia of Eastern Philosophy and Religion says “Advaita-Vedanta teaches that the manifest creation, the soul, and God are identical.” It tells us that Shankara (788-820), the main representative of Advaita-Vedanta, uttered, “Brahman alone is real, the world is appearance, the Self is nothing but Brahman.”
Amit Goswami, a retired professor of quantum physics from the University of Oregon, is a self-admitted Vedantist, which helps to explain the books he’s written (The Self-Aware Universe, The Physics of the Soul) and the films he’s been in (What the Bleep?, The Secret) since he retired.
Erwin Schrodinger, of “Schrodinger’s cat” (is it alive or dead or somehow both, when we haven’t seen the outcome?) is said to have been attracted to the teachings of the Vedanta back in the 1930s, as well.
To suggest that a Jewish agnostic psychiatrist in New York in the 1960s who finds herself “taking shorthand” for a voice that calls itself Jesus and provides over 800 pages of manuscript that’s later called A Course in Miracles and transforms humanity’s idea of the Son of God, the Holy Spirit, and the nature of reality “Advaistic” seems a stretch, but somehow isn’t too far wrong!