Now, before some of you jump down my throat, please use two of the Fruits of the Spirit: patience and self-control. Read what I say (I will try to keep it short) and then jump down my throat, if you still need to. 
First off, a little background…. the reason that Jews were allowed to remain Jewish when Rome controlled Judea is because they invited Rome in to help them get rid of the Seleucid kings. When the followers of Yeshua (Jesus) began to grow, they were made up of Jews, and of Gentiles (mostly Romans) converting to Judaism. However, by the end of the 1st Century, Rome had problems with the Jews and were persecuting them, but it was NOT a religious persecution. It was a political persecution because the Jews were rebelling against Roman authority. As such, the Jews following “the Way” and the newly converting Gentiles began to separate themselves from the persecuted Jews, which was to be safe from persecution. That backfired, because as they started to form a new religion, that was not acceptable to Rome, and so the (now called) Christians were persecuted; this was a religious persecution. In the 3rd Century, along comes Constantine and he converts to Christianity (now very different from Judaism) and he makes it even more separate, essentially creating modern Christianity.
That brings us up to Christmas. Constantine had a problem, which was how to make Christianity more popular to a people who have worshiped Roman gods for centuries, and most likely will not be as happy to trade them off as Constantine is. The answer: re-boot the holidays! Take the celebratory feeling that comes with their big holidays, and redirect it to a new holiday with the same feel, but make it a celebration of Messiah instead of a pagan god. This is why I don’t think Christmas is so bad- it isn’t worshiping a pagan god, it isn’t a pagan holiday, and it never was. Saturnalia WAS a pagan holiday that worshiped a pagan god, but Christmas was created to celebrate the birth of the Messiah. I believe a lot of the anti-Christmas feeling comes from the fact that it was placed at the same time as the pagan celebration. The reason for that was not to put a different face on the same holiday, but so that it would easily fit into their schedule, and that made it easy for Constantine to switch focus/worship of the population from paganism to Christianity.
Here’s the point- Christmas is not Saturnalia with a new name, it is a totally new and different celebration; Saturnalia was rejected and done away with. Just as the Golden Calf was rejected and destroyed, so too did Constantine do away with Saturnalia, and it was replaced (NOT re-instituted, but replaced!) with Christmas, which is from it’s inception a celebration of Messiah’s birth.
Now, the fact that the birth of Messiah was months earlier in the calendar isn’t relevant to the topic, which is that Christmas was never a pagan holiday. Christmas was created as a righteous memorial to Messiah, and was “timed” to occur at the same time as an old, now rejected, pagan holiday so that it would be an “easy sell” to the populace.
Therefore, I don’t see anything wrong with Christmas so long as the people celebrating it are celebrating Messiah Yeshua. If you really want to come down on someone, come down on the retail companies that have prostituted this celebration into a social event that has made gift giving more important than celebrating the birth of our Messiah.

One last note: Joseph’s brothers conspired to murder him, but Joseph later understood something that I think we need to relate to Christmas (Genesis 50:20): “But as for you, ye thought evil against me; but God meant it unto good, to bring to pass, as it is this day, to save much people alive.” What had been an unrighteous pagan celebration has been replaced and changed into a righteous celebration of the Messiah, who is the ultimate means of saving people’s lives. I think celebrating the birth of our Messiah, whether on the correct day or not, is always a good thing, no matter how it started or where it came from.