Billions of people celebrate Christmas on December 25th, but did you know that scholars aren’t sure when Jesus was born? The best evidence suggests the Nativity occurred in 5 B.C., but competing theories span several years. Much of the confusion traces back to a 6th-century monk named Dionysius, who skipped “Year 0” and jumped straight from 1 B.C. to 1 A.D. when creating the modern calendar. Another complicating factor is the precise dating of key historical events, such as the death of Herod and the journey of the Magi. This article walks through leading theories about when Jesus was actually born and explains the 4th-century origins of December 25 as a Christian holiday.
Did you know? We specialize in historical and religious topics, including articles about the Christmas Story in Luke and How the Apostles Died.
Table of Contents
The Main Source of Confusion: Why the Calendar Is Off
Our modern calendar system originated in 525 C.E. when Pope John I asked a monk named Dionysius Exiguus to calculate future Easter dates. Dionysius delivered—but he made some mistakes.
At the time, years were often counted from the reign of the Roman Emperor Diocletian, a notorious Christian persecutor. Dionysius found this reliance on the “Era of the Martyrs” distasteful. So, he proposed a new “Anno Domini” (“in the year of our Lord”) epoch that counted years from Christ’s birth.
Dionysius relied on the Julian calendar to estimate that Christ was born in the Roman year 753. Then, he redesignated it as “Year 1” of his new system, positioning the Incarnation at the center of Christian chronology.
How Did Dionysius Exiguus Change the Calendar?
Dionysius (pronounced dye-uh-nish-ee-us) made several changes to the calendar that complicate efforts to estimate the date of Christ’s birth:
- Confusing Timeline: While not a mistake, it can feel strange to measure historical events in two directions (before and after Christ’s birth).
- Miscalculating the Reign of Caesar: Dionysius’s calculation may have been off by 4-6 years.
- Skipping “Year 0”: He didn’t have any concept of “zero”, so Dionysius moved directly from 1 B.C. to 1 A.D.
- Later Corrections (Gregorian Reform): It wasn’t Dionysius’s fault, but the underlying Julian calendar was inaccurate to the tune of about 11 minutes per year. By 1582, it had “drifted” a full 10 days. More than an error, it reflected poorly on the Church for not knowing when Easter fell during the Protestant Reformation, so the Council of Trent mandated a correction. The resulting Gregorian Calendar was more accurate, but never became popular enough to replace what Dionysius had established.
B.C.E. and C.E. Meaning
Further complicating matters, scholars replaced Dionysius’ religious calendar abbreviations with secular ones:
- B.C. (Before Christ) = B.C.E. (Before Common Era)
- A.D. (Anno Domini) = C.E. (Common Era)
It’s confusing in the best of circumstances—and that’s before trying to pinpoint dates of relevant historical events.
From Bethlehem’s Star to Herod’s Death: Dating Other Historical Events
While the four Gospels don’t always align—or “harmonize”—they do provide historical clues about Christ’s birth date that scholars can verify with secular sources outside the Bible. Some of the most noteworthy “historical anchors” for the Nativity are dates for Herod’s death, the Census of Quirinius, and the Star of Bethlehem.
1. Reign and Death of Herod the Great
Both Matthew and Luke agree that Jesus was born before Herod’s death, making it the most important “historical anchor.”
The Jewish historian Josephus adds more detail, indicating that Herod died shortly after a lunar eclipse and just prior to Passover. Astronomers have found several possible candidates, creating a window for Jesus’s birth between 7 and 4 B.C.E.
In the 19th century, archaeologists found evidence that Herod died in 4 A.D., meaning that Dionysius’s 1 A.D. date for Jesus’s birth wasn’t possible. However, by then, the calendar was so ingrained in daily life that the mistake wasn’t corrected (Pope Benedict XVI even wrote a book about it).
2. Census of Quirinius
Luke 2:2 says that Jesus was born during the “first registration” while Quirinius was governing Syria. But there are all sorts of debates about what this refers to.
Most scholars think that it refers to the real (but misdated) Census of Quirinius in 6/7 C.E. or the existence of an earlier unrecorded event around 8-5 B.C.E.
3. Star of Bethlehem
The “Star of Bethlehem” (Matthew 2:1–12) serves as the primary astronomical anchor for the Nativity. Astronomers don’t know exactly what the star was, but they have found several possible options:
- Triple Conjunction: In the 17th century, Johannes Kepler suggested that the Star of Bethlehem was actually Jupiter, Saturn, and Pisces appearing together in 7 B.C.E. Jupiter was the “King Planet,” Saturn was associated with Jews, and Pisces was a zodiac sign of the West or the end times. This rare “Great Conjunction” could have suggested a significant royal birth in the West.
- Planetary Massing and the Molnar Theory: Astronomer Michael Molnar proposes a 6 B.C.E. theory that claims the “star” was Jupiter passing by the moon in the constellation Aries. Because Aries was the astrological symbol for Judea, the “healing rising” of Jupiter may have signaled the birth of a new ruler to ancient astrologers.
- Comets in the Far East: Chinese and Korean documents from 5 B.C.E. record the appearance of a “broom star” or comet—likely a nova or supernova—that remained visible for more than 70 days. Its stationary position and lack of a comet’s “tail” matched the biblical description of a star “standing over” a specific location.
- All of the Above: Some believe that the “star” of the Magi was not a single event, but rather a sequence of astronomic events beginning with the 7 B.C.E. triple conjunction and concluding with the 5 B.C.E. nova.
Debates about when these events occurred play a key role in calculating a variety of birth dates for Jesus. There are also competing theories for what led to the first celebration of Christmas as a religious holiday on December 25 in the 4th century.
The Development of the December 25th Tradition
The most popular theories for the origins of December 25th as a Christian religious holiday tend to incorporate the historical context or rely on mathematical calculations.
The “History” Hypothesis
This theory evaluates the cultural context of the first documented celebration of Christmas in the 4th century. The idea holds that the Church wanted Christmas to capitalize on popular pagan festivals held at the same time.
Rather than celebrate the winter solstice in accordance with Roman traditions, Christians would form a new annual holiday to honor Christ as the “Sun of Righteousness.”
The “Calculation” Hypothesis
The genesis of this approach is a belief shared by ancient Jews and Christians that great prophets died on the same calendar dates as their births.
Since early Christians believed that Christ was crucified on March 25, that meant he would have been conceived on the same date years earlier. Add nine months for Mary’s pregnancy, and you get a December 25 birth date.
What Year Was Jesus Born? Examining Key Theories
Current scholarly consensus pinpoints a narrow window of 6-5 B.C.E. to accommodate both Herod’s death and the events that followed the birth of Christ. This majority position is one of several well-known theories for birth years that range from 6 to 1 B. C. E.
6-4 B.C.E.
Scholarly Consensus
The majority of historians accept this window because it accounts for Herod’s death in 4 B.C.E., allows time for the Magi’s journey and flight into Egypt, and aligns with a historical comet that could have been the “star” of Bethlehem.
No other theory incorporates more data points, and most Christian scholars now believe that Jesus was born sometime during 5 B.C.E.
3 B.C.E.
Fringe/Astronomical Theory
Ernest L. Martin argues for a birth in 3 B.C.E., relying on a “late Herod” death date in 1 B.C.E. This contradicts Josephus’s account and archaeological evidence, but aligns with a theory that Herod’s successors may have backdated their reigns.
It also interprets Revelation 12:1-5 as an “astral prophecy” that pinpoints a unique alignment of Virgo, the sun, and the moon precisely on September 11, 3 B.C.E.
6-1 B.C.E.
Denominational Theory (Latter-day Saints)
1 B.C.E.
Some members of The Church of Jesus Christ of Latter-day Saints think that Jesus was born on April 6, 1 B.C.E. This interpretation is based on a literal reading of Doctrine and Covenants 20:1, which states that the church’s 1830 organization took place “one thousand eight hundred and thirty years since the coming of our Lord and Savior Jesus Christ in the flesh.”
The theory has faded in the wake of scholarship from the Joseph Smith Papers, showing that verse 1 wasn’t part of the original revelation and doesn’t support a literal interpretation. Nonetheless, it was popular for decades and constitutes a unique and widespread denominational approach to finding the actual birthday of Jesus.
4-6 B.C.E.
Ongoing research by Latter-day Saint scholars also yields a variety of views. For example, BYU Professor Jeffrey R. Chadwick has used the Book of Mormon to pinpoint Jesus’s birth month as December 5 B.C.E.
Conversely, other BYU scholars such as Thomas Wayment and Lincoln Blumell have argued for a three-year range based solely on the strongest evidence.
Winter, Spring, or Fall? Pinpointing the Nativity’s Time of Year
There’s no consensus for the season of Christ’s birth—other than that it likely was not in the late summer. Scholars have narrowed most options down to six months of the year:
- Winter (Dec/Jan): The “Calculation Hypothesis” relies on mathematical calculations based on historical events that yield a December birth. Some critics say this isn’t a viable theory because Judean shepherds would have kept their flocks under cover during the rainy winter season.
- Spring (March/May): This theory is favored by those who connect Christ’s birth to the spring lambing season, when shepherds would be in their fields overnight. It also aligns with the Chinese “broom star” of 5 B.C.E. and carries symbolic weight, as the “Lamb of God” would have been born during the season when Passover lambs were selected for ritual sacrifice.
- Fall (Sept/Oct): The “Priestly Course of Abijah” theory provides a systematic way to work backward from the conception of John the Baptist to the birth of Christ. Luke 1:5 states that John’s father, Zechariah, belonged to the course of Abijah—one of 24 priesthood groups mentioned in 1 Chronicles 24 that served in the Temple. His rotation occurred in late May or early June, meaning John could have been conceived shortly after and born nine months later. Luke 1:26 adds that Jesus was conceived in the sixth month of Elizabeth’s pregnancy. Thus, Jesus’s estimated birth month would fall in September or October.
Despite the lack of agreement on precisely when Christ was born, the question itself reveals an importance that goes beyond dates and figures.
Beyond the Calendar: Why It Matters
No date perfectly aligns with all the evidence, even though a 5 B.C.E. estimate comes close. But for many contemporary Christians, the issue is about more than choosing the “best” theory. On a deeper level, it anchors Christianity’s central claim—the Incarnation of Christ—within the verifiable flow of human history.
The question of Christ’s true birth date can also be meaningful on a personal level. The search for a tangible detail, such as a birthday, enables a connection with the divine on an intimate level.
In theory, that, in turn, enables seekers to better emulate Christ’s teachings to love one another, regardless of when the historical Jesus was born.
Frequently Asked Questions
The best evidence points to a 5 B.C.E. birth year. However, several competing theories cover the period from 6 to 1 B.C.E.
We don’t know. Scholars have narrowed the options to six months, including December when Christmas is traditionally celebrated.
Dionysius estimated that Christ was born in the Roman year 753, which he designated as “Year 1” of his “Anno Domini” calendar.
Dionysius didn’t have a concept of “zero,” so he jumped straight from 1 B.C. to 1 A.D. (It wasn’t until nearly 1,000 years later that Arab tutors taught Fibonacci the functional uses of zero).
The Bible records a star that guided the Magi to the infant Christ. While some argue this was a literary device, others have identified astronomical events the Gospels may refer to, including the Chinese “broom star” and the rare Triple Conjunction of 7 B.C.E.
Further Reading
Explore more From the Desk articles about the historical context of the Nativity:
- What Led to the Christmas Story In Luke?
- Does the Book of Mormon Say When Christ Was Born?
- Who Was the Virgin Mary in Early Christianity?
- Did Herod the Great Claim to Be the Messiah?
- How Did the Twelve Apostles Die?
Resources: When Is Jesus’ Real Birthday?
Read what top scholars and publishers say about calculating the actual date of the Incarnation:
- When Was Jesus Born—B.C. or A.D.? (Biblical Archaeology)
- Textual Evidence for Jesus’ Birth Year (Britannica)
- The Bible’s Star of Bethlehem May Have Been a Comet (Smithsonian Magazine)
- Pope Says Christian Calendar Based on Miscalculation (ABC News)
- Herod’s Death, Jesus’s Birth, and a Lunar Eclipse (Biblical Archaeology)
