When Was Jesus Born? It Wasn't Actually Dec. 25

Before we even get to the month and day debate, historians generally agree that we've got the year of Christ's birth all wrong. How can that be, though, if "year 1" on the Gregorian calendar was based on the year that Jesus was born?

The short answer? The man who invented the idea of anno Domini (shortened to A.D.), or "Year of Our Lord," was off by several years.

Even Pope Benedict XVI agreed in a 2012 book that Dionysius Exiguus, the sixth-century monk who first calculated the year of Jesus' birth, miscounted, and that Jesus was likely born between 7 B.C. and 2 B.C. (Note that modern writers often use "C.E." for "Common Era" instead of "A.D." and "B.C.E." for "Before Common Era" instead of "B.C." or "Before Christ" to be more inclusive and avoid religious references when denoting years.)

One compelling reason for an earlier birth year is that the Bible mentions in several places that Jesus was born when Herod the Great was king of Judea.

However, according to Flavius Josephus — the famed Roman-Jewish historian who lived in the first century C.E. — King Herod died in 4 B.C.E.

If we take Josephus' word for it, Jesus must have been born at least four years earlier (probably more) than our calendar says.

"We have this modern obsession with dates and chronological order, but the gospel writers were much more interested in theology than chronology," says Ian Paul, a theologian, biblical scholar and author who blogs at his website Psephizo.

That said, Paul's best guess for the true date of Jesus' birth is somewhere in September, based on a complex set of calculations related to the birth of John the Baptist, also mentioned in Luke.

A fall date for Christmas makes sense when you consider that the shepherds were in the fields tending their flocks, a sign of mild weather. Paul says that by December, the Judean foothills outside of Bethlehem are cold enough to get snow.

Ultimately, whether the life of Jesus began in December, September or March doesn't change the true meaning of Christmas. Still, the debate over Jesus' "real" birthday shows just how difficult it is to place specific dates on events in ancient history.

The popular theory that Christians chose Dec. 25 to co-opt the pagan solstice festival of Sol Invictus is not based on strong evidence but on the margin scribblings of an unnamed Syrian monk in the 12th century.

Rather than accusing Christians of stealing the holiday, he was offering a theory for why Western churches "moved" Christmas from January to December, only days away from the winter solstice.

In fact, the first mention of a date for Christmas was around 200 C.E., and the earliest celebrations date back to 250–300 C.E., "a period when Christians were not borrowing heavily from pagan traditions of such an obvious character," according to the Biblical Archaeology Society.

Connections to Easter

For centuries after Jesus' death, people of the Christian faith didn't pay much attention to his birthday. In those days, early Christians were persecuted and even martyred for their beliefs, which led them to put an emphasis on Easter, when they believe Jesus was martyred on the cross but overcame death and was resurrected.

It wasn't until the third and fourth centuries C.E. that early Christian writers and theologians put forth possible dates for Jesus' birth. Even then, those dates were related to Easter. In ancient times, Paul says, there were traditions that the lives of great men were connected to specific times of the year.

Heroic figures often died in the same month and on the same day that they were born (years apart, of course). In Jesus' case, it seems that ancient sources believed he was either born or divinely conceived during Passover, the springtime Jewish holiday during which he was later crucified.

Christians who believed Jesus was conceived around Passover/Easter counted nine months ahead to identify his birthday. In Rome and other Western locales, they calculated Passover in the year that Jesus died as occurring on March 25.

Eastern Christian communities used a Greek calendar that placed the same Passover on April 6. Add nine months, and early Christianity came up with two traditional Christmas dates: Dec. 25 and Jan. 6.

So why do biblical scholars like Ian Paul believe that the actual traditional date for Christmas ought to be in September? This theory comes from a close reading of the clues left behind in Luke, particularly what the gospel's authors had to say about the timing of the birth of John the Baptist in relation to Jesus.

Luke's version of the Christmas story doesn't begin with Mary and Joseph. Instead, it starts with another couple, Elizabeth and Zechariah, who were older and childless.

Zechariah, a priest, was visited by the angel Gabriel in the temple. Gabriel told him that his wife would have a son named John, who would prepare the world for the coming of the Lord.

Zechariah doubted Gabriel's message and was struck dumb. But when his service in the temple was over, the priest went home, and Elizabeth soon became pregnant.

As it turns out, the angel Gabriel also visited Mary to tell her she was going to conceive and give birth to baby Jesus, the Son of God, even though she was a virgin. Luke tells us that this second visitation to Mary happened "in the sixth month of Elizabeth's pregnancy."

With that key fact, it's possible to deduce that Jesus was conceived six months after John. But that only helps us if we know when exactly John was conceived. And how would we know that?

More Biblical Clues

Again, the Bible provides more clues. Luke tells us that Zechariah "belonged to the priestly division of Abijah." Each division of priests took turns performing sacrifices and other services in the temple. In 1 Chronicles 24, the order of temple service is laid out by divisions numbering one through 24, with Abijah listed as eight in the rotation.

As Paul calculated on his blog, if each priestly division served for one week, with the first week of the ecclesiastical calendar landing in late March, that would put Zechariah in the temple in early June. If Elizabeth conceived soon after the angel visited Zechariah, and Mary conceived six months later, it places Jesus' birth in September of the following year.

Paul likes the September theory of Christmas for several reasons, including the shepherd idea mentioned above. Would Luke have placed shepherds in the fields in the middle of winter?

However, there are also some holes in this theory.

The biggest problem is that each priestly division served more than once a year in the temple. What if Gabriel appeared to Zechariah during his second stint in the temple six months later? That would place Jesus' birth in March, which Paul admits is a distinct possibility.

Ultimately, how important is it to solve the mystery of Jesus' actual birth date?

Thomas Wayment is a professor of classical studies at Brigham Young University who has written about the competing theories regarding the timing of Jesus' birth. He finds the debate over his birthday to be intellectually fascinating and worthy of discussion, but he also thinks it misses the point spiritually.

"Maybe, just maybe, we're better leaving it open in a sense," he says. He has seen early Christian references to Jesus' birth in April, May, and December and January. "We're celebrating an event, not a day."

We updated this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.