I'm not sure how obvious this is in Singapore or the USA: but it seems to me that Christmas has developed into 2 separate holidays - one Christian and the other secular.
Save for the name, practically nothing people associate with the Christmas holidays has anything to do to at all with Jesus or Christianity: gifts, family & friends, feasts, decorated trees, candy cane, snowman, Santa Claus, log cakes, mistletoe etc. There actually are non-Christian Christmas celebrations (obviously...).
So here, enjoy this video by TheThinkingAtheist regarding Christmas traditions.
On a related note, I just want to say that atheists can celebrate whatever holiday, religious or not, if they want to. I'm just not celebrating the myths -- if anything, the secular aspects (friends, family and common values etc) are what's worth celebrating.