Over at the Atlantic, Oliver Sacks expertly discusses the neurology of out of body experiences (OBE) and near death experiences (NDE). While some people interpret these experiences as religious, these interpretations are highly dependent on cultural milieu and personal proclivity. It is a fascinating fact that those who interpret these brain-states as religious nearly always claim to have an experience relevant to the religion that is dominant in their culture or life.
I’ve come across numerous accounts of OBE/NDE type experiences in the Native American ethnohistoric record, and these always mirror dominant cultural percepts. Around the world, there is a near perfect correlation between culture and interpretation: Americans who interpret OBE/NDEs as religious express Christian themes. Indians interpret them as Hindu, Thais interpret them as Buddhist, Indonesians interpret them as Muslim, etc.
If people were truly experiencing something real or ultimate outside of their heads, we might expect these interpretations to be more uniform, universal, or consistent. The common theme seems to be that the culture in which one is immersed massively conditions the experience and its subsequent interpretation.