Although we celebrate the birth of Christ on December 25, nobody knows the month, or even the year, when he was actually born. What we do know is that the Romans held their Feast of the Unconquered Sun on December 25 as part of Saturnalia and the Celtic festival Yuletide coincided with the winter solstice, when the days are at their shortest, around December 22.
Saturnalia marked the overthrow of the father-god, Saturn, by his son Jove and it was a fire festival. Romans decorated their homes with branches of greenery, candles and coloured lanterns. There were services of thanksgiving and an exchange of presents, wrapped in coloured cloth, and there was much feasting and merry-making.
Celtic customs were also absorbed into the new festival. When, in the third century AD, the church set the date of Christ's birth, midwinter was chosen in order to sanctify these vigorous pagan traditions and, like the Christmas wreaths and the Boxing Day pantomime, many of them still survive at the end of the 20th century as part of the Christian festival.