I don't celebrate it. I'm not fussed that others do or anything, I don't moan about it coming up. I'm single and due to being socially awkward I am rubbish at buying gifts that people would like. I don't have any belief in a god either, so I decided it's best to just not bother anymore.
It was something I was bullied for in a previous job. Some people didn't like that I wasn't joining in putting decorations up or talking about what they were going todo, wearing hats and things so I was called a "bah humbug" and was not included in non-christmas things.
The thing is, the company was an Indian company and we had lots of Indian people working there too, who didn't celebrate Christmas. Apparently it was ok because they have a different celebration in their religion , but it wasn't acceptable for me to not celebrate it even though I said I wasn't religious.
Edit: I actually thought I'd show that I didn't hate christmas one year so sent my colleagues cards and they said why am I doing that if I don't celebrate christmas (in a manner that was trying to make me look like I had no integrity) and I said I don't but you do. The card is wishing you a good christmas. But they didn't understand that logic.