Christmas is not a Biblically mandated holiday. So we are free to celebrate it any way we choose or not celebrate it at all.
For those of us who choose to celebrate the Lord's birth on this day it is a holy day. For others it is at least a warm , family time. It is a celebration adapted from a pagan winter festival. So it is not exclusively a Christian holiday.
Merchants are in business to make money. They have every right to promote their business heavily at this time of the year. But to do so IMO is not a violation of the purpose or spirit of Christmas. I can praise God for His Son no matter how "commercial" the merchants get. Rather than criticizing others for the way they celebrate Christmas I believe the best thing we Christians can do is share with them what and why we celebrate the way we do.
In Him,
Bob Allen