Well, we do, but we're really, really bad at it. Back in the first world war, both sides took some time off for Christmas. This was the so-called "Christmas Truce." They exchanged presents. They had music. They played football. Not real football, but soccer. They call it "football" to hide the fact that it's really just a bunch of small guys running around for a couple hours not scoring.
We won't play soccer against the Afghanis and Iraqis, and they won't play real Football or Baseball (they play cricket) against us, and also they don't celebrate Christmas. So, basically we have to challenge them to hoops.
There's a pretty good movie about the Christmas Truce called "Joyeux Noel". The History Channel special is also available.