Christmas is celebrated on the 25th of December because it's a Christian holiday that commemorates the birth of Jesus Christ. The date was chosen because it was believed to be the day Jesus was born, according to the Bible. However, some historians and scholars have suggested that Jesus' birth actually occurred during a different time of year, perhaps in the spring or autumn. Nonetheless, the 25th of December has been widely accepted as the date of Christmas for centuries, and it continues to be celebrated by millions of people worldwide.