"Hypotheses have been around for 20 years connecting the beginning of religions with psychoactive materials," Shanon says. He believes the Israelites used two plants in Sinai and the Negev: one of them is wild rue, a hallucinogen used by the Bedoin to this day. However this plant is not identified with any plant mentioned in the Bible.

The acacia tree also has psychedelic properties, Shanon says, which the Israelites could have used. The acacia is mentioned frequently in the Bible, and was the type of wood of which the Ark of the Covenant was made. According to Shanon, he drank a potion prepared from a species of acacia while he was in South America, which caused similar experiences to those produced by the ayahuasca.
That makes the whole thing easier to swallow for me, not such a leap of faith. But no less valid as a religious experience. I think shamans (prophets) have a deeper connection to the spiritual when using certain naturally occuring chemicals than the average joe getting high for fun.