Christmas was once a moveable feast celebrated at many different times during the year. The choice of December 25 for the official date of Christ’s birth was made by Pope Julius I, in the 4th century A.D., because this coincided with the pagan rituals of Winter Solstice, or Return of the Sun (on December 20–23). The intent was to replace the pagan celebration with the Christian one.
In ancient times people from all over the world celebrated winter festivals. The Romans celebrated Saturnalia festival honoring Saturn – the god of agriculture. Germanic pagans celebrated Yule or the return of sun god. Many of the modern Christmas traditions such as bedecking houses and churches with tree branches, huge gifting and arranging grand feasts are apparently derived from these pagan celebrations.