According to Osho, Kundalini sadhana is psychic—pertaining to the subtlest layers of body-mind—not spiritual in itself. Like a diving board, it is a necessary platform that can propel you toward the soul. Breath, food, and thought are material supports; rightly used, Kundalini work prepares the leap into the nonmaterial, the truly spiritual.
It’s a mind-energy practice that uses body and breath to help you reach spirit, but it isn’t spirit itself.