Alexander Hislop (1807-1862) was a Scottish Protestant minister famous for his outspoken criticisms of the Roman Catholic Church.

He wrote several books, his most famous being The Two Babylons: Papal worship Revealed to be the worship of Nimrod and His wife. This book was initially published in 1853 as a pamphlet, then greatly revised and expanded and released as a book in 1858.

He claimed the Roman Catholic Church was a Babylonian mystery cult, and pagan, whereas Protestants worshipped the true Jesus and the true God. He contended that Roman Catholic religious practices are actually pagan practices grafted onto true Christianity during the reign of Constantine. At this point, he alleged, the merger between the Roman state religion and its adoration of the

Hislop's theory was that the goddess, in Rome called Venus or Fortuna, was the Roman name of the more ancient Babylonian cult of Ishtar, whose origins begun with a blonde-haired and blue-eyed woman named Semiramis.

According to Hislop, Semiramis was an exceedingly beautiful white woman, who gave birth to a son named Nimrod, a large, ugly black man, and later married him, thus founding Babylon, and its religion, complete with a pseudo-Virgin Birth. This he called a foreshadowing of the birth of Christ, prompted by Satan. Later, Nimrod was killed, and Semiramis, pregnant with his child, claimed the child was Nimrod reborn.

Hislop claimed that the cult and worship of Semiramis spread globally, her name changing with the culture. In Egypt she was Isis, in Greece and Rome she was called Venus, Diana, Athena,

Then, according to Hislop, Constantine, though claiming to convert to Christianity, remained pagan but renamed the gods and goddesses with Christian names to merge the two faiths for his political advantage, under Satan's guidance.

The book has been severely criticized for its lack of evidence, and in many cases its contradiction of the existing evidence: for instance, the Roman state religion before Christianity did not worship a central Mother Goddess, and Jupiter was never called "Jupiter-Puer." Likewise, Semiramis lived centuries after Nimrod, and could neither have been his mother, nor married him. Hislop also makes unacceptable linguistic connections and fanciful word plays, e.g. the letters IHS on hosts in Catholic Holy Communion are alleged to stand for Egyptian deities Isis, Horus and Seth, but in reality they are an abbreviation for Ihsous, the Latin spelling of Jesus's name in Greek (Ιησους), although popularly, they stand for the Latin Iesus Hominum Salvator meaning Jesus, Savior of Mankind (which also fits the teaching of Transubstantiation, where the bread and wine are said to become the body and blood of Christ).

Despite this, and the fact that his book, if proven true, would discredit Christendom as a whole, since the concepts that it attacks in Catholicism are shared by some Protestants, this book was, and still remains in some circles, a staple of anti-Catholic polemic. Hislop is a favorite source of Jack Chick, who published reprints of his book, and Dave Hunt, who on occasion alludes to his work. While strong criticisms of this book have been published, it is still considered by many as a definitive work of Protestant Christian apologetics.

Other books by Alexander Hislop include Scottish Anecdotes and Proverbs of Scotland (1862).