I have to say as an atheist, I enjoy Christmas music (but only about two weeks prior to the event). I enjoy Christmas even if I do decorate my fake apple tree which is no less pagan than an evergreen.
I don't mind anyone enjoying Christmas as it is a celebration of group mythology from the virgin birth to solstice to Santa Claus. It is fun and a reason to enjoy visits from my very ecuminical family. We are all something but mostly not Christian.
I do say Merry Christmas to people. Why not? It is a cheerful greeting. I decorate with toys and other non-christian symbols. It doesn't threaten my atheism tho my atheism seems to threaten Christians.
Christians seem to think we as athiests should have cold, dark, joyless Celebrations of the season rather than enjoying the time off from work, the food, the glitter and the presents. We somehow don't deserve joy because we don't believe.
Well I do believe in joy, and I like parties and presents. The thing is I can enjoy watching old movies in my pajamas while other people have to go to church. I can take my kids sledding on Christmas eve instead of dressing them up and herding them to church.
I find joy in the sounds and scents and carols.
I like chocolate rabbits at Easter too.
I also get to enjoy Halloween. And make a family celebration any old time.
Often people say atheist have no reason to laugh or have joy. We are all grim intellectuals with no sense of humor and no holidays.
I get to enjoy holidays because Ihave no guilt. I have no stress that I may not be doing everything right. I don't have to impress a diety I don't believe in. I can just be in peace and happiness.