Well, Christmas is a complicated holiday in general. If you want to know what it's about, it depends on who you ask.
Christians that call themselves Christians despite not being really religious: It's Jesus's birthday! :D
JWs: BS, no one knows Jesus's birthday!
Muslims / Jews: Pagan BS (The star on the tree? Halos? Sun-worship subliminal messaging? Is that all just a coincidence?)
Muslims that celebrate Christmas (I've never met any, and I can't imagine ANY Muslim dare celebrating a christian thing. If there are people like this, I pity you lot. Pick up a Qu'ran yo): It's just family togetherness!
Atheists (Danaos / Spartacus): Money money money
Iclandish people: (probably something to do with testicles) Well, there's 7 Santas, and this and this and that *completely different version of Christmas than the American version*
Which proves why Christmas is a bunch of BS in general. So yeah.