The Reason for the Season

Charlie Brown: Everything I do turns into a disaster. I guess I don't really know what Christmas is about. Isn't there anybody who understands what Christmas is all about?
Linus Van Pelt: Sure, I can tell you what Christmas is all about.

And there were in the same country shepherds abiding in the field, keeping watch over their flock by night. And lo, the agent of the Lord came upon them, and the glory of the Lord shone round about them, and they were sore afraid. And the agent said unto them, "Fear not, for behold, I bring you tidings of great joy which will be to all people. For unto you is born this day, in the City of David, a savior, which is Christ the Lord. And this shall be a sign unto you. Ye shall find the babe wrapped in swaddling clothes and lying in the manger." And suddenly, there was with the angel a multitude of the Heavenly Host, praising God and saying "Glory to God in the Highest, and on Earth peace, good will towards men."

That's what Christmas is all about Charlie Brown.

I hear so much talk this time of year about how the holidays should be advertised and celebrated. "Jesus is the reason for the season" and "Keeping the Christ in Christmas". Signs scattered around neighborhoods, making clear what those people think Christmas is all about. But is it? Where did Christmas come from exactly? Where did it all start? Is there actually any mention of "Christmas in the bible? Where did all of tehses Christmas traditions come from? Why do so many people get bent out of shape about "Happy Holidays"?