The Bible tells us that when the Children of Israel left Egypt, they had a 40-year trip through the desert before reaching the Promised Land. Now a leading Israeli academic has a new theory about exactly what kind of trip it was.

In the philosophy journal Time and Mind, Benny Shanon states that key events of the Old Testament are actually records of visions by ancient Israelites high on hallucinogens. Shanon is a professor at Jerusalem's Hebrew University, where he used to head the psychology department.

The psychedelic substance is a drink called Ayahuasca. It is extracted from plants that grow in the Holy Land and in the Sinai peninsula and is still used today by Amazonians in Brazil for their religious rituals. Shanon came up with his theory when reading the Bible. The events described reminded him of the visions he had after trying this drink 15 years ago. So, when Moses first encountered God, he was high. "Encountering the divine is one of the most powerful experiences associated with high-level Ayahuasca inebriation," claims Shanon.

At the Burning Bush, covered in flames but mysteriously not consumed, there was no miracle, just a drug-induced "radical alteration in the state of consciousness of the beholder - that is, Moses". The account of the Children of Israel hearing God while camped at Mount Sinai is about a mass drug-taking event - giving a whole new explanation for the reported "cloud of smoke" that settled on the mountain. And when Moses climbed Sinai and received the Ten Commandments and the Bible, he was tripping.

Hardly an incident in the Bible is spared Shanon's drug-focused reading. Acacia trees, used by Noah to build the ark, were revered because some varieties contain the psychedelic substance dimethyltryptamine (DMT). In Shanon's opinion, the Tree of Knowledge in the Garden of Eden offered something far more tempting than an apple.

Rabbis in Israel and the UK are largely ignoring Shanon's theories, and those who have spoken out have been dismissive. "The Bible is trying to convey a very profound event. We have to fear not for the fate of the biblical Moses, but for the fate of science," Rabbi Yuval Sherlow told Israel Radio. Israeli internet chatrooms, though, are buzzing with condemnations of "heresy", endorsements, and charges that Shanon, not Moses, must have taken drugs. One poster writes: "Maybe it is true - then religion really is the opiate of the people."