Seasons greetings! You've been linked some great stuff already, but I thought you might also like this recent thread from /u/lord_mayor_of_reddit.
Merry Christmas! Not to discourage further answers, but you might be interested in:
What was considered the true meaning of the pre-Christain winter festival that we know as Christmas today? answered by u/BRIStoneman
What are the historic facts about December 25th and Christmas? by u/talondearg
Is anything in this 'wiccan' meme/comic abput the pagan origins or Christmas symbolism accurate? by u/itsallfolklore