The story centres on the widely made claim that, when numerised (i.e., when those letters in the 'title' that have roman numeral value are added together), they produce the number 666, described in the Book of Revelation as the number of the Beast (the Antichrist) which wears multiple crowns identified by some as the triple tiara). This claim has been made by some Protestant sects who believe that the Pope, as head of the Roman Catholic Church is the Beast or the False Prophet mentioned in the Book of Revelation. However, a detailed examination of the existing tiaras shows no such decoration.
Further, Vicarius Filii Dei is not among the titles of the Pope; the closest match is Vicarius Christi ("Vicar of Christ", also rendered in English as "Vicar of Jesus Christ"), the numerical values of which do not add up to 666.
There is also a dispute on the numerology of "Vicarius Filii Dei" and "Vicarius Christi". Latin does not have the letter 'U' but instead uses 'V'; only if one uses the correct Latin spelling VICARIVS·FILII·DEI is the total produced (VICIVILIIDI = 5 + 1 + 100 + 1 + 5 + 1 + 50 + 1 + 1 + 500 + 1 = 666) (Vicarivs Christi, the real title, comes up to 214). Otherwise, the numbers add up to 661 and 209.
The time period for this claim is traditionally given as AD 855–858, between the reigns of Leo IV and Benedict III; however, this possibility is unlikely, because Leo IV died on 17 July 855, and Benedict III was elected as his successor on 29 September of the same year.
Jean de Mailly, a French Dominican at Metz, places the story in the year 1099, in his Chronica Universalis Mettensis, which dates from approximately 1250 and gives what is almost certainly the earliest authentic account of the woman who became known as Pope Joan. His compatriot Stephen of Bourbon acknowledges this by placing her rule at approximately 1100. Also, Rosemary and Darrell Pardoe, authors of The Female Pope: The Mystery of Pope Joan. The First Complete Documentation of the Facts behind the Legend, are assuming that a more plausible time-frame would be 1086–1108, when there were a lot of antipopes, and the reign of the legitimate popes Victor III, Urban II and Paschal II was not always established in Rome, since this city was occupied by Emperor Henry IV, and later sacked by the Normans.
Generally, there are two versions of the legend.
"Joan" disguises herself as a monk, called Joannes Anglicus. In time, she rose to the highest office of the church, becoming a pope.
After two or five years of reign, Pope Joan became pregnant, and during an Easter procession, she gave birth to the child on the streets when she fell off a horse. She was publicly stoned to death by the astonished crowd, and according to the legend, removed from the Vatican archives.
As a consequence, popes throughout the medieval period were required to undergo a procedure wherein they sat on a special chair with a hole in the seat. A cardinal would have the task of putting his hand up the hole to check whether the pope had testicles.
In a seventeenth-century study, Protestant historian David Blondel argued that 'Pope Joan' is a fictitious story. The story may well be a satire that came to be believed as reality. This view is generally accepted among historians.
Some hold that the current pope, Benedict XVI, will be the penultimate Pope, based on the Prophecy of the Popes. This claim cannot be proven either true or false until the end of the reign of Pope Benedict XVI's successor.
There have been several Popes who were alleged to have been sexually active during their reign, or even to have died as a result of this, as claimed by various authors in history.
However there is no solid evidence for any of these claims; in history, there has been only one document that was attributed to Jesus himself, the Letter of Christ and Abgarus. Scholars generally believe that those letters were fabricated, probably in the 3rd century AD. Even in ancient times, Augustine and Jerome were to the effect that Jesus wrote nothing at all during his life. The correspondence was rejected as apocryphal by Pope Gelasius I and a Roman synod (c. 495).