Academic Editor: Dyron B. Daughrity Received: 21 July 2025 Revised: 5 August 2025 Accepted: 7 August 2025 Published: 9 August 2025 Citation: Ascough, Richard S. 2025. John Allegro and the Psychedelic Mysteries Hypothesis. Religions 16: 1029. https://doi.org/10.3390/ rel16081029 Copyright: © 2025 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/ licenses/by/4.0/). Article John Allegro and the Psychedelic Mysteries Hypothesis Richard S. Ascough School of Religion, Queen’s University at Kingston, Kingston, ON K7L 3N6, Canada; rsa@queensu.ca Abstract John Allegro’s The Sacred Mushroom and the Cross posits that early Christianity derived from fertility cults involving psychedelic mushroom use. Though widely discredited by scholars when it was first published, the theory persists in popular culture and entheogenic discourse. This article evaluates the scholarly reception, methodological flaws, and en- during cultural impact of Allegro’s thesis, particularly its role in the broader psychedelic mysteries hypothesis. Although Allegro’s linguistic methodology has been rejected by most experts, his work has contributed to renewed interest in the role of entheogens in religious traditions, with some scholars attempting to salvage Allegro’s intuitive insights while distancing themselves from his linguistic excesses. Due to its foundational methodological flaws, however, Allegro’s work is best viewed as a historical curiosity rather than a reliable source for contemporary entheogenic scholarship. Keywords: altered states of consciousness; early Christianity; entheogens; linguistic methodology; mushrooms; psychedelic mysteries hypothesis; religious experience; shamanism 1. Introduction Despite widespread academic criticism and disdain, John Allegro’s thesis in The Sacred Mushroom and the Cross (first published in 1970) continues to find traction in popular arguments for the presence of psychedelics in the ancient western religious traditions. Carl Ruck, in writing an addendum for the fortieth anniversary republication of the book, cites new supporting evidence while slamming the mainstream academy for ignoring or twisting Allegro’s (2009) arguments. All this to maintain that, despite admitted methodological flaws, Allegro’s work is still useful in support of the psychedelic mysteries hypothesis. We can see a trend toward this way of holding the ancient religious psychedelic hypothesis even as more humanities scholars continue to engage with entheogenicist claims, such as in public events like Harvard’s Center for the Study of World Religions hosting a conversation between scholar of early Christianity, Charles Stang, and Brian Muraresku, author of The Immortality Key. This event was sponsored by, among other institutions, Esalen, which regularly convenes scholars to work on the deep questions of human spiritual experience, practice, and potential, and Chacruna Institute for Psychedelic Plant Medicines founded by anthropologist Bia Labate. Existing work on Allegro has given fair due to the question of whether Ruck is correct that Allegro is a maligned and misunderstood scholar, or was he in fact a scoundrel, deliberately seeking to be sensationalistic in order to draw attention to himself (Hanegraaff 2012; cf. Jacobsen 1971, p. 246)? Re-examining the arguments on both sides shows that Allegro’s approach fails to take seriously the available evidence for the role of psychoactive substances in religious experiences in antiquity and thus cannot be treated as a reliable source for contemporary entheogenic scholarship. Religions 2025, 16, 1029 https://doi.org/10.3390/rel16081029