Since the early 20th century, many Mormons have thought they knew the exact date of the first Christmas. Elder James E. Talmage, an apostle of The Church of Jesus Christ of Latter-day Saints, published a book in 1915 titled "Jesus the Christ," in which he wrote, "We believe that Jesus Christ was born in Bethlehem of Judea, April 6, B.C. 1."

Elder Talmage didn't just randomly make up this date. He took it from Section 20 of the Doctrine and Covenants — a collection of revelations mostly through the Mormon founding prophet, Joseph Smith Jr. Since his book, Mormons — from church leaders to children — have accepted April 6 as the real date of Jesus' birth. But not every member of the LDS Church agreed with Elder Talmage's interpretation of Doctrine and Covenants 20.

Jeffrey R. Chadwick, an associate professor of church history and doctrine at BYU, published an article in the latest issue of BYU Studies on "Dating the Birth of Jesus Christ" that challenges the popular but not universal Mormon dating of Jesus' birth to April 6.

And he is in good company.

In 1954, President J. Reuben Clark Jr., a counselor in the First Presidency of the LDS Church, wrote that Christ's birth was in December of 5 B.C. or early 4 B.C.

In 1979, Elder Bruce R. McConkie, also an apostle, favored December 5 B.C. as well as alternative dates in 4 B.C.

The date of April 6 comes from the date that the LDS Church was originally organized in 1830. D&C 20 begins with this introductory verse: "The rise of The Church of Christ in these last days, being one thousand eight hundred and thirty years since the coming of our Lord and Savior Jesus Christ in the flesh, it (the church) being regularly organized and established agreeable to the laws of our country, by the will and commandments of God, in the fourth month, and on the sixth day of the month which is called April."

Steven C. Harper, a BYU assistant professor of church history and a volume editor of the Joseph Smith Papers, said in a phone interview that some people, including Elder Talmage, have read this verse as if it is the Lord speaking and revealing precisely that Christ was born 1,830 years before that day and that the revelation was given on April 6, 1830.

The recent discovery of the Book of Commandments and Revelations manuscript of D&C 20, however, showed that the verse was actually an introductory head note written by early church historian and scribe John Whitmer — something he did for many of the revelations, Harper said. "So those are separate from the texts that Joseph produces by revelation."

The manuscript, published as part of the Joseph Smith Papers, also shows that the revelation was given on April 10 — not April 6. So although it references the organization of the church a few days earlier, the revelation — which topically has nothing to do with the birth date of Christ — and its introductory verses "shouldn't be read as if it is a revelation of the birth date of Jesus Christ," Harper said. "The interpretation that has been most popular over time is very much subject to question; that's all I'm saying."

And this wasn't the only time that John Whitmer would identify a date with similar language. Another time he wrote, "It is now June the twelfth, one thousand eight hundred and thirty one years, since the coming of our Lord and Savior in the flesh."

In other words, this type of language was merely a fancy 19th-century way of saying the date.

If a person accepts Chadwick, Harper, Elder McConkie and President Clark's interpretation of the verse in D&C 20, when was Jesus born?

Chadwick's article goes into great detail on the various clues the Bible and the Book of Mormon give for the date of Jesus' birth.

The biggest clue, by far, appears to be the death of King Herod the Great. The Bible has Jesus born before Herod's death. Chadwick wrote that the historical record places Herod's death at the end of March or beginning of April in 4 B.C. This date is confirmed by both the mention of a lunar eclipse before Herod's death and the date his son was deposed by Caesar Augustus. Both those fixed events fit together to confirm Herod's death.

Needless to say, if Herod was dead in 4 B.C., a 1 B.C. birthday of Christ is impossible.

So if Jesus had to be born before April 4 B.C., can the time be narrowed further?

Chadwick's article in BYU Studies goes on for pages, using fixed dates to extrapolate other dates. He looked closely at the time of Jesus' death, for example, tied it to the length of Jesus' life given in the Book of Mormon, added such things as time for Jesus' circumcision eight days after his birth, Mary's 40 days of ritual purification, the visit of wise men from the east and a two-week journey to Egypt. All those events show that "at a minimum, Jesus would have to have been born eight weeks prior to Herod's death at the beginning of April (4 B.C.)."

Chadwick then looks at the Annunciation to Mary that she would have a son named Jesus. Luke 1:26 placed this event in the sixth month — which at the time was from mid-to-late February to mid-to-late March. March of 5 B.C.?

Add nine months.

"When all is said and done," Chadwick wrote, "the facts from the New Testament, the Book of Mormon, and the history of Josephus, combined with input from archaeological and astronomical research, all point to a day in December of 5 B.C. (late in the Jewish month of Kislev) for the date of Jesus' birth."

This means that the real date of Christmas may have, indeed, been on Dec. 25.

"It is just as possible that Jesus was born on the calendar date we call Dec. 25 as on any other date in the few weeks preceding it or following it," Chadwick wrote. "(H)is birth occurred within those December weeks that we now commonly refer to as the Christmas season."