why is christmas day on december 25th

The exact origins of Christmas Day being on December 25th are not entirely clear, but there are several theories. One theory suggests that the date was chosen because it was already a significant day for the Roman Empire, which used it as a celebration of the winter solstice and the birth of the sun god, Mithras. Another theory suggests that December 25th was chosen because it was believed to be the day that Jesus was born. This belief is based on the Gospels of Matthew and Luke, which both state that Jesus was born in Bethlehem during the reign of King Herod, who died in 4 BC.