The Two Babylons, subtitled Romanism and its Origins, is a book that started out as a religious pamphlet published in 1853 by the Presbyterian Free Church of Scotland theologian Alexander Hislop (1807–65).

Hislop provides a detailed comparison of the ancient religion which was established in Babylon (allegedly by the Biblical king Nimrod and his wife, Semiramis) by drawing on a variety of historical and religious sources, in order to show that the modern Papacy and the Catholic Church are the same system as the Babylon that was mentioned by the apostle Paul in the first century (when he commented on the iniquity that was already creeping into the 1st century Christian church[2]) and the author of Revelation.

[3] Some modern scholars have rejected the book's arguments as erroneous and based on a flawed understanding of the Babylonian religion, but variations of them are accepted among some groups of evangelical Protestants.

[7] 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 its inspiration from Babylon.

[8] Much of Hislop's work centers on his association of the legendary Ninus and his semi-historical wife Semiramis with the Biblical Nimrod as her husband and her son, with their incestuous male offspring being Tammuz.

In the note by the editor of the 7th edition, which was published in 1871, it was claimed, "that no one, so far as we are aware, has ventured to challenge the accuracy of the historical proofs adduced in support of the startling announcement on the title page."

For example, Lester L. Grabbe has highlighted the fact that Hislop's entire argument, particularly his association of Ninus with Nimrod, is based on a misunderstanding of historical Babylon and its religion.

[17] Although Hislop's work is extensively footnoted, some commentators (in particular Ralph Woodrow) have made the assertion that the document contains numerous misconceptions, fabrications, logical fallacies, unsubstantiated conspiracy theories, and grave factual errors.

[18] Some fundamentalist Protestants still regard Hislop's book as proof that the Roman Catholic Church is, in fact, the continuation of the ancient Babylonian religion.

[4] In 1921 A. W. Pink confidently asserted that Hislop's work had "proven conclusively that all the idolatrous systems of the nations had their origin in what was founded by that mighty Rebel, the beginning of whose kingdom was Babel.