In 274 CE the Roamn Emperor Aurelien officially set the date of December 25th
natalis Solis Invicti (the birthday of the inconquerable Sun) in honour of the Sun God. The festival took place just after Winter Solstice, when the days became longer.
The Roman Emperor Constantine (fourth Century CE) was converted to Christianity. Alliances were formed between Constantine and the early Christian Church, and in 324 he made Christianity the official religion of Rome. In 349 CE Pope Julius formally selected December 25th as the birth date of Christ, and so began the celebration of Christmas and the arrogation of seasonal Pagan symbolism and religious theme.
The Christmas traditions 'borrowed' from Pagans were the yule log, bringing an evergreen tree into the house and decorating it, celebrations, games, food and drink, frankincense and mirth are also Pagan things, representing life and death..
Germanic Pagans used to celebrate Yule (winter solstice) for 12 days, hence the 12 days of Christmas.
The fatman climbing down your chimney originated from Germanic Pagans also, but it was a troll who would crawl down your chimney and eat you if you were bad...
This information is readily available on the net if any Christians wish to challenge it...
it seems the bible being so strong is really quite fragile these days...