Excerpted from Good Tidings of Great Joy, 72
Whereas the settling of the date of Christmas on December 25 was a post-biblical development (see How Christmas Came to Be on December 25), attempts to identify the year of Jesus’ birth have been based on several passages in the Infancy Narratives themselves. Matthew 2:1 and Luke 1:5 seem to place the birth before the death of Herod the Great in 4 B.C, a date which is also supported by Luke 3:1–2. Luke 2:2 dates the birth of Jesus to the governorship of Quirinius or “Cyrenius,” which began in A.D. 6. This difference of at least 10 years between these two dates cannot be reconciled easily with the evidence currently available.
Of course neither of these dates accords with the modern Western calendar, which suggests that Jesus was born in A.D. 1, with A.D. standing for anno Domini, or “the year of our Lord.” This dating system was established about A.D. 500 by a monk named Dionysius Exiguus, who calculated that Jesus was born 754 years after the traditional founding of Rome. With that point of reference, he reorganized the calendar with the birth of Christ as the central point, with all events before it leading up to it and all after being counted from it. Because it is most likely that a date before Herod’s death in 4 B.C. is correct, it is clear that Dionysius miscalculated.
Given the probability that Jesus was born in 5 or 4 B.C., it is probable that the notice in D&C 20 that the Church was reorganized “one thousand eight hundred and thirty years since the coming of the Savior Jesus Christ in the flesh” is a conventional date expression based upon the calendar that Joseph Smith was using at the time. Likewise, attempts to correlate Book of Mormon notices about the birth and death of Jesus must take into account the complexities involved in correlating ancient calendars, including the differences between lunar and solar calendars (see Omni 1:21) and uncertainties about Nephite practices of intercalation, or adding days into their calendar, that may have been used to keep their years in line with the seasons.
Kelley, Origins of Christmas, 56–57.
Joseph Fielding McConkie and Craig J. Oslter, Revelations of the Restoration: A Commentary on the Doctrine and Covenants and Other Modern Revelations (Salt Lake City: Deseret Book, 2000), 155.
David Rolph Seely, “Chronology, Book of Mormon,” Book of Mormon Reference Companion, edited by Dennis L. Largey (Salt Lake City: Deseret Book, 2003), 196, 198–99; Holzapfel, Huntsman, and Wayment, Jesus Christ and the World of the New Testament, 112.