I have two good friends who are atheist... and they love xmas. They don't care about baby Jesus, or angels, or the religious message. They like the traditions of gift giving, decorating, and having parties. They both decorate their houses, put up trees, etc. One guy is a big sci-fi fan, so all his tree ornaments are Star Wars, Star Trek and various other sci-fi related decorations. The other guy uses three or four generations of ornaments handed down, both religous and secular.
I've asked them about their love of the holiday and they verify that it's just tradition and enjoying it along with everyone else and enjoying the season... and watching their kids enjoy it.
So, I've kind of adopted their philosphy and I enjoy certain aspects of the season. The music, the parties, the xmas spirit that is there, even if it creates shopping and traffic headaches. I don't care about decorating or entertaining so much, though I don't turn down too many xmas party invites.
There may be religious reasons behind the actual holiday, but it has evolved into different things for different people.