Where Christmas came from is IMHO irrelevant. What was its initial purpose equally so. What is important is what Christmas represents now to those who choose to celebrate it. For me, it is the time when people really should take the time out of their busy schedules to spend some time with their families and loved ones. We can talk all day about the need to spend every day with your loved ones, but the truth of the matter is that we all lead busy lives or our loved ones do, and so we are not always able to spend enough time with each other. So when the world throws you an opportunity and an expectation, I say go for it.
And if not that at least celebrate the three shortest days of the year and welcome the lengthening days which after the 26th, which signify the coming of Spring!!!