The Bible says Jesus was born on December 25

Luke and Matthew both narrate the birth in detail: the census, the shepherds, the inn, the magi. But neither dates it to a specific day or even a season. Luke does include one detail some scholars use to argue against a winter birth: shepherds are out in the fields at night with their flocks (Luke 2:8), a detail some read as pointing toward spring or early autumn lambing season rather than winter, though this argument isn't decisive on its own.

December 25 is first clearly attested as Jesus's birth date in the 4th century, and historians genuinely disagree about why that date was chosen. One long-standing theory ties it to the Roman winter-solstice feast of Sol Invictus, suggesting the church reclaimed a popular pagan festival date. A rival theory, argued by scholars like Andrew McGowan, works from a Jewish and early Christian calendrical tradition that connected a prophet's conception and death to the same calendar date: since March 25 was reckoned by some early Christians as the date of the crucifixion, adding nine months of gestation lands on December 25 independent of any solstice connection. Either way, it's a later Christian decision about how to commemorate the event, not something either Gospel states.