His book "Warrant for Genocide" is on the "Protocols of the Elders of Zion", the anti-semitic forgery purporting to describe a Jewish conspiracy for world domination. He argued that this conspiracy theory motivated its supporters to seek the of the Jewish people and became a major psychological factor in the Nazi Holocaust. In "Cosmos, Chaos and the World to Come: The Ancient Roots of Apocalyptic Faith" (1993), he sought to trace the source of millennial religious themes in ancient civilizations. Cohn, with his background in dealing with totalitarian regimes and the sufferings of his relatives during the Holocaust, described all his work as studies on the phenomena that sought "to purify the world through the annihilation of some category of human beings imagined as agents of corruption and incarnations of evil". His work was honoured by his election as a Fellow of the British Academy, for which he was nominated by Isaiah Berlin. His "The Pursuit of the Millennium" was ranked as one of the 100 most influential books of the 20th century in a survey conducted by "The Times Literary Supplement".