It's not exclusively Christmas time, Ed. It never was. Before a certain radical religious reformer was born in Judaea, this time of year - the Winter Solstice - was already a festival time. The Maccabees intentionally selected it for the celebration of Hanukkah to counteract the attractive pagan rites that already had hundreds of years of precedence. There's a persistent rumor (I haven't been able to verify, yet) that the Feast of the Nativity was placed at the same time for the same reason, since there's no clue in Gospel as to the time of year of that event. (cf. the widespread practice in the Roman Empire of Mithraism, a Persian religion which also marked the birth of their deity at the Winter Solstice).

If you look into it in detail, there are dang few Christian celebrations that have not been tacked right onto an existing pagan holiday, most of which involved some change of the seasons. In fact, many of the traditional celebration elements have solid pagan roots, including Easter eggs, Christmas trees, mistletoe, and many others. The early monks knew how to sell a religion without making waves. It doesn't take much thinking to realize that shepherds would probably not be watching their flocks at night in the fields in the middle of the winter.

Many of our other Christmas traditions, like the current image of Santa Claus, are even more recent, with most less than a hundred years old. Wish I was ambitious enough to dig up links for all this stuff.

Someone showed me a cross that Norsemen wore in early Christian days there that could be either a cross or a hammer of Thor, depending on where you happened to be hoisting the mead cup that day.