[Captain.Remy]

No they should not. They don't believe in anything and they want to celebrate Christmas without knowing what it this and what does it represent to a kind of people.
It's like if Muslims celebrate Hannukah, it's not right.
After all, Atheists can find their own day and everyone will be happy.

And Sticks, I know many people who don't recognise it and who are christians but it doesn't mean they want atheists to celebrate it instead.

And it's the same thing for Easter. People want presents or chocolates but when you talk about the religion meaning they are like "Oh no no no I don't trust in anything....but I still want presents !"