Moreover, the song they agree on is about as non-controversial as you can get—the celebration of riding across the snow in a "one-horse open sleigh". And, Jingle Bells has no real religious connotations. In fact, it only talks about having fun (remember that?)—making reference to "laughing all the way". When was the last time you laughed even part of the way?
Scanning the list of responses, it's interesting that pretty much half the songs simply celebrate the season—without specific reference to anything religious. This fits the American model. It is precisely our commitment to being a secular nation that allows religious liberty to flourish. So, let's all throw open our windows and "sing this sleighing song" tonight.