OK - should parp myself at this. But what is "tradition"? Traditions evolve and grow over time. Including how we currently celebrate Christmas... This is what I found outlining Christmas and it's evolution, which describes a lot of why we do the things we do at Christmas...
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In the Western world, the birthday of Jesus Christ has been celebrated on December 25th since AD 354, replacing an earlier date of January 6th. The Christians had by then appropriated many pagan festivals and traditions of the season, that were practiced in many parts of the Middle East and Europe, as a means of stamping them out.
There were mid-winter festivals in ancient Babylon and Egypt, and Germanic fertility festivals also took place at this time. The birth of the ancient sun-god Attis in Phrygia was celebrated on December 25th, as was the birth of the Persian sun-god, Mithras. The Romans celebrated Saturnalia, a festival dedicated to Saturn, the god of peace and plenty, that ran from the 17th to 24th of December. Public gathering places were decorated with flowers, gifts and candles were exchanged and the population, slaves and masters alike, celebrated the occasion with great enthusiasm.
In Scandinavia, a period of festivities known as Yule contributed another impetus to celebration, as opposed to spirituality. As Winter ended the growing season, the opportunity of enjoying the Summer's bounty encouraged much feasting and merriment.
The Celtic culture of the British Isles revered all green plants, but particularly mistletoe and holly. These were important symbols of fertility and were used for decorating their homes and altars.
New Christmas customs appeared in the Middle Ages. The most prominent contribution was the carol, which by the 14th century had become associated with the religious observance of the birth of Christ.
In Italy, a tradition developed for re-enacting the birth of Christ and the construction of scenes of the nativity. This is said to have been introduced by Saint Francis as part of his efforts to bring spiritual knowledge to the laity.
Saints Days have also contributed to our Christmas celebrations. A prominent figure in today's Christmas is Saint Nicholas who for centuries has been honoured on December 6th. He was one of the forerunners of Santa Claus.
Another popular ritual was the burning of the Yule Log, which is strongly embedded in the pagan worship of vegetation and fire, as well as being associated with magical and spiritual powers.
Celebrating Christmas has been controversial since its inception. Since numerous festivities found their roots in pagan practices, they were greatly frowned upon by conservatives within the Church. The feasting, gift-giving and frequent excesses presented a drastic contrast with the simplicity of the Nativity, and many people throughout the centuries and into the present, condemn such practices as being contrary to the true spirit of Christmas.
The earliest English reference to December 25th as Christmas Day did not come until 1043