Mohabat News -- In "Jesus of Nazareth -- The Infancy Narratives," the pope says the Christian calendar is actually based on a blunder by a sixth century monk, who Benedict says was several years off in his calculation of Jesus' birth date, CNN reports.
According to the pope's research, there is also no evidence in the Gospels that the cattle and other animals traditionally pictured gathered around the manger were actually present.
He also debunks the claim that angels sang at the birth, a staple theme of Christmas carols.
The book, which is being published in multiple languages in time for Christmas, is the third in a series by the pontiff. The previous two volumes dealt with Jesus' adult life and his public ministry.
Alessandro Speciale, Vatican correspondent for the Religion News Service, told CNN the pope was not so much aiming to debunk myths as trying to show that the Jesus depicted in the Gospels is a real historical figure, who walked on earth and talked to people like anyone else.
The pope also looks at scholarly studies of the Bible, some of which have indicated for decades that the traditionally accepted birth date for Jesus is wrong, Speciale said.
But while the book points out that the Gospels do not support the presence of animals at Jesus' birth -- a detail apparently added in later centuries -- the pope does not suggest they should be thrown out of the Nativity scene, Speciale said.
"The pope is a traditional man and he doesn't want people at all to change their traditions," Speciale said.
The 176-page volume, which comprises a brief foreword, four chapters and an epilogue, traces Jesus' life up to the age of 12, when, according to the Gospels, he was presented by his parents in the Temple in Jerusalem, the Vatican said.
The initial worldwide print run is more than a million copies, it said, with the book released this week across 50 countries in Italian, German, Croatian, French, English, Polish, Portuguese and Spanish.
In the coming months, the book will be translated into 12 more languages for publication in 72 countries in total, the Vatican added.
The Vatican quotes Anthony Valle, a professor of theology, as saying the pope has been open to scientific inquiry in his own study of Jesus' life.
"The pope is not against the historical critical method at all, in fact, he uses it, he appreciates it," Valle said.
He sees the pope as using "both faith and reason" in his efforts to bring the life of Jesus closer.
Monsignor Philip Whitmore, who translated the book into English, said the pontiff used his writing to explore "the inner meaning of the infancy narratives, showing how they pick up on Old Testament themes and develop them in new and unexpected ways."
"The pope helps us to understand the world where Jesus was born. Caesar brought peace to the Roman Empire, but this tiny child brought something much more wonderful: God's peace, eternal life, an end to sin and death," Whitmore added.
"Anyone who's wondering why Christmas came to be such a great celebration in the West can find the answer right here. The pope explains how the birth of Jesus changed history forever."