The modern Christmas tradition started as consumer goods became increasingly cheap, so that each year became a boost to the economy. A month before Christmas in the US, the Friday after Thanksgiving became known as "Black Friday" due to stores going from "red" debt to "black" growth. While there are amusing takes on Christmas consumerism, I will talk on other aspects.
Christmas, however, existed long before then. It originated from a number of pagan and heathen Winter Solace-based celebrations around Europe. One was the Roman holiday of Saturnalia, a drunken festival. Another was the Norse Yule. In the Norse celebration, the chief god Odin (appearing as an old man with a beard and red outfit) would fly around hunting monsters in his Wild Hunt. Children left out their stockings with carrots inside for Odin's horse Sleipnir, in hopes the All-Father would leave them gifts.
When Christianity spread, missionaries would adopt local symbols, customs, and traditions to "convert" the locals. Witness Odin becoming Saint Nick. Often times, the best way to assimilate a conquered people is co-opting their own traditions. The current incarnation of Christmas, for instance, has become synonymous with gifts, snow, and Santa Claus around the world. From Spanish colonization of the New World to Christians sending armed missionaries to convert at sword-point in the Dark Ages to countless other instances, Christmas itself has potential for supervillainy. Just imagine a world ruled by Santa, perhaps getting in touch with his Norse roots.