'God within us', those plant substances that, when ingested, give one a divine experience, in the past commonly called 'hallucinogens', 'psychedelics', 'psychotomimetics', etc etc, to each of which serious objections can be made. A group headed by the Greek scholar Carl A.P. Ruck advances 'entheogen' as fully filling the need, notably catching the rich cultural resonances evoked by the substances, many of them fungal, over vast areas of the world in proto- and prehistory. See Journal of Psychedelic Drugs Vol 11.1-2, 1979, pp 145-6. We favor the adoption of this word. Early Man, throughout much of Eurasia and the Americas, discovered the properties of these substances and regarded them with profound respect and even awe, hedging them about with bonds of secrecy. We are now rediscovering the secret and we should treat the 'entheogens' with the respect to which they were richly entitled. As we undertake to explore their role in the early history of religions, we should call them by a name unvulgarized by hippy abuse."
Generally used in place of "psychedelics" or "hallucinogens" by wannabe Hippies playing as much semantics as the Bush administration.
Actual shaman probably would laugh at the people who call hallucinogens this term because physical and psychological trials usually accompany the ingestion of hallucinogenic substances in shamanistic cultures and these people just sit in the comfort of their air conditioned parents' house and think they're getting in touch with the divine.
Used by people with no knowledge of anthropology and those who would probably be considered Orientalists by those who don't live in Western societies.