why do we celebrate xmas on dec 25

Christmas is celebrated on December 25 because it is believed to be the day when Jesus Christ was born. The date is based on the Christian calendar, which counts the years from the estimated birth of Jesus. Many people also believe that the date was chosen because it coincides with the winter solstice, which is the shortest day of the year and marks the beginning of the winter season. Additionally, many people also believe that the date is significant because it is close to the pagan holiday of Saturnalia, which was celebrated by ancient Romans.