(Image Credit: L'Osservatore Romano/AP Photo)

Jesus was born earlier than previously believed, meaning the Christian calendar based on the year of his birth is off by several years, the Pope argues in his new book.

The book, "Jesus of Nazareth: The Infancy Narratives," is on sale now around the world with an initial printing of 1 million copies. In it, the head of the Catholic Church asserts that the Christian calendar is based on a miscalculation because Jesus was born sometime between 7 B.C. and 2 B.C., the Telegraph reported.

"The calculation of the beginning of our calendar - based on the birth of Jesus - was made by Dionysius Exiguus, who made a mistake in his calculations by several years," Pope Benedict XVI writes. "The actual date of Jesus' birth was several years before."

The Christian calendar was created by an Eastern European monk named Dionysius Exiguus. He invented the now commonly used Anno Domini (A.D.) era, which counts years based on the birth of Jesus. He came up with this concept in the year 525, or, 525 years after the birth of Jesus.

This claim isn't a new one, and will likely not have any consequences, but it is the first time the leader of the church has stated publicly such doubts about one of the keystones of Catholic tradition.

The assertion that Jesus was born earlier than Dionysius Exiguus believed means the Christian calendar, based on his birth year, is off by several years. The Bible does not specify when Jesus was born, and it seems Dionysius based his calculations on vague references to Jesus' age.

This is one of several new arguments the pope, 85, makes in the book. He also says that, despite what most people think of as a typical nativity scene, there were no animals present at Jesus' birth.

The book is the final installment of Benedict's trilogy. The first book dealt with Jesus' public ministry, and the second with his death. Both previous books topped bestseller lists in Italy. All three books are published under the pope's real name, Joseph Ratzinger, who was born in Germany.