Christian: ...? that's a Nativity scene. it's a symbol of what Christmas is all about. how can you not know that?
Atheist: oh. i don't believe in Jesus, but I'll gladly piss on your traditions to get a present. I'll celebrate the secular holiday "Christ-less-mas".
I don't celebrate Christmas, dude.
So what're you doing on 25 December, bro?
I'm having a huge Christlessmas lunch, dude. Everyone's invited. Party on!