BS.
Christmas isn't evil.
Yes, a pagan festivity, the winter solstice, had been adapted for christianity.
I can see nothing wrong with that.
Imagining hungry and freezing people in ancient times, longing for the sun to come back and end the times of winter, many couldn't survive, is a comprehensibly wish.
Dressing up a (still green) tree in the midst of winter means to ad fruit (this is what ornaments symbolise) to the tree.
This is the hope that winter might end and that the people will find again plenty of food to survive.
I can understand this hope.