The The Handbook of Near-Death Experiences: Thirty Years of Investigation details an experimental protocol to test for disembodied consciousness, otherwise known as “apparently nonphysical veridical perception” (as quoted here):
In a place where NDEs are likely to occur, plant some perceptual stimulus and then interview everyone who survives a near-death episode in the vicinity of that stimulus to determine whether they perceived it … Place the stimulus so that it is perceivable by an NDEr but not by other people in the area; in fact, to rule out the possibility that an interviewer or others might intentionally or unintentionally convey the content of the stimulus to the NDEr through normal—or even paranormal—means, arrange it so that the stimulus is not known even to the research team or associates.
Adaptation to other disembodied consciousness
While this test is geared towards NDEs, it could be applied to other purported disembodied conciousness. For instance, if a person claims to be in communication with the Holy Ghost or Holy Spirit, the Spirit should have the ability to peer into a closed container with a 14 phrase password written on paper within and then communicate the password.