Dr. Gregory Shushan of Oxford University "...examines the relationship between afterlife conceptions and conceptually-related anomalous experiences in ethnohistoric indigenous traditions worldwide." In 2012 he gave a lecture at the Ian Ramsey Centre for Science and Religion which compared the components of NDEs to the religious texts of numerous ancient civilizations. His work convincingly shows that NDEs have inspired afterlife conceptions among world cultures from ancient times. That is, NDEs appear to be a causal inspiration of religious belief from ancient times, not an illusion produced as the result of religious belief.
He is also the author of the book Conceptions of the Afterlife in Ancient Civilizations.
Dr. Shushan's full lecture can be seen online at this location.