Here's my atheist perspective on the whole thing...
It is true that Christmas was based around Yule that the pagans celebrated,
but they also took Halloween from the Christians.
So should we re-name Thursday because we don't believe in Thor?
Late November/December is when I tend to be least well, so I have
reservations about it. I do enjoy Christmas, though - both its family and
its church aspects - even though I am usually pretty flaked out by the time
it arrives.