Solstice! The day the sun stops its steady crawl to the south and looks northward once again. In the picture below the sun is rising at its southernmost point. The far left margin of the picture (or perhaps a little beyond) is where it will rise on the Equinox and it will travel the same distance again to rise on the Summer Solstice way over there. (Yes, I know it's the Earth moving, not the Sun but this is what it looks like. I'm using Poetic License here.)
Imagine primitive Man, especially in the northern regions, -- watching the days grow shorter and the nights grow longer and wondering where it would all end. Perhaps they thought that a spot of sympathetic magic was in order -- so they lit fires to drive away the dark and recall the sun to its duty. And we still do, in some ways, keep those fires burning against the darkness by celebrating and giving thanks with light and fellowship and food.
Though Christmas and Hanukkah and, perhaps, Yule are the holidays/holy days most widely celebrated at this time in my part of the world, there have been and are any number of festivities at the Winter Solstice -- honoring Mithras in Rome, Baldur in Scandinavia, Ameratsu in Japan, to name a few. (See more HERE.) Indeed, many scholars believe that December 25 was designated as Christ's birthday to compete with the Pagan festival of Sol Invictus (the triumphant Sun.)
Here in the Northern Hemisphere, dark December needs all the light it can get. The return of the Sun and the promise of another growing season ahead should speak to all. I say, the more celebrations, the merrier --- whatever your belief (or non-belief.) Solstice time belongs to everyone under the Sun.