The Two Babylons, subtitled The Papal Worship Proved to Be the Worship of Nimrod and His Wife is a religious pamphlet published in 1853 by the Presbyterian Free Church of Scotland theologian Alexander Hislop (1807–65). It was expanded in 1858, going through many editions. A 3rd edition was published in 1862, a 7th in 1871, a popular edition in 1903. It has been claimed on many websites that The Two Babylons was only finally published as a book in 1919, though the third edition reached 500 pages in length.
Its central theme is its allegation that the Catholic Church is a veiled continuation of the pagan religion of Babylon, a product of a millennia-old conspiracy.
Hislop builds on the Panbabylonian school of Hyperdiffusionism, which was common in the 19th century, to argue that Classical and Ancient Near Eastern civilization took all its inspiration from Babylon, and from that he derived the argument Mystery Religions of Late Antiquity were actually offshoots of one ancient religion founded at the Tower of Babel. Panbabylonism has since been relegated to pseudohistory.
Much of Hislop's work centers on his association of the legendary Ninus and his semi-historical wife Semiramis with the Biblical Nimrod. Hellenistic histories of the Ancient Near East tended to conflate their faint recollections of the deeds of ancient kings into legendary figures who exerted far more power than any ancient king ever did. In Assyria, they invented an eponymous founder of Nineveh named Ninus, who supposedly ruled 52 years over an empire comparable to the Persian Empire at its greatest extent. Ninus's wife Semiramis was in turn a corruption of the historical figure Shammuramat, regent of the Neo-Assyrian Empire from 811 BC. Hislop takes Ninus as a historical figure, and associates him with the Biblical figure Nimrod, though he was not the first to do so. The Clementine Literature made the association in the 4th Century AD. An influential belief throughout the Middle Ages was that Ninus was the inventor of Idolatry, a concept that Hislop clearly drew upon. However, Hislop wrote before the historical records of the ancient near east had been thoroughly decoded and studied, and it became apparent in the decades after he wrote that there never was any such figure as Ninus, and that the Greek authors whom he quotes were without credibility on the subject.