In 1970 the British Dead Sea Scrolls philologist John Allegro published The Sacred Mushroom and the Cross, arguing that Christianity began as the coded literary shell of a secret fertility cult centered on eating the hallucinogenic mushroom Amanita muscaria, with the New Testament itself read as a cipher built from Sumerian word roots. The book was received with near universal rejection: dozens of British scholars of Semitic languages, theology and biblical studies signed a joint letter published in The Times repudiating Allegro's philological method as unsound, and no subsequent New Testament scholarship has adopted or built on his central claim. Part of the case Allegro and earlier mushroom cult writers pointed to was the Plaincourault fresco, a thirteenth century French wall painting of the Garden of Eden in which the Tree of Knowledge is rendered with a distinctly mushroom like canopy, read by mushroom cult proponents as coded evidence that medieval Christian art still carried a memory of the entheogenic origin.
R. Gordon Wasson, whose own 1968 book Soma had proposed Amanita muscaria as the sacred plant of the Rig Veda, investigated the fresco directly and, after consulting the art historian Erwin Panofsky, concluded the tree was not a mushroom at all but an example of a widespread medieval convention for stylizing pine and other trees, documented in numerous other contemporary works with no plausible mushroom connection. Wasson published this finding himself, against the reading that would have supported his own broader thesis, a detail historians of the debate treat as evidence of his methodological seriousness.