It all depends on your perspective, for a long time of its history, Christmas was not a religious holiday at all. It was originally called "Saturnalia, a roman holiday celebrating the win of a war with the giving of presents. Infact it was a meld of many roman and pagan holidays, combined with the rise of the catholic church (that also renamed it to "christmas"), that turned it into what it is today. So by no means is it "supposed" to be christian, there are many ways to celebrate it, but if that's how you celebrate it its perfectly fine.