We all know, (at least we all should know) that Christmas and Easter were originally pagan festivals, "baptised" into Christian use. We do not know when the actual birth of Christ was, and I dear say that God hid the real time deliberately for the very reason we see today, how it has been commercialised and secularised. The 25th December was originally a day of annual sun worship for pagan Rome, and as for Easter, the original festival was passover, and had nothing to do with the current astrological system that commands the time.
That said, I love both occasions. As a previous poster said, there is an "atmosphere" of joy, peace, and benevolence that is sadly missing throughout the rest of the year. Though I, like Agua, sing carols everywhere I go, I don't celebrate the days per se, but certainly use them to witness because even the most secular of people are willing to listen to the gospel at Christmas and Easter.
The fact is that others do celebrate the day, especially Christmas, and there are many elderly and single people or those estranged from family who particularly at this time are alone and feeling particularly lonely. This time of year is an opportunity to touch the lives of these folk with the love of Jesus, revealing to them the truth of the precious gift that our heavenly Father has bestowed upon the human race, His own Son.
Sorry, didn't mean to start preaching. Merry Christmas everyone.