This is why I don't do ANY holiday related "teaching" or "crafts"
I'm personally not big on celebrating holidays anyway, but other than that, we live in a VERY diverse country and there will almost always be a family who practices other beliefs. I would not want a teacher or provider teaching my kids about holidays/rituals/etc. that I didn't agree with, and I respect other families in the same way.
I realize that this family does celebrate Chritmas, but do understand their choice to be honest with their child.
Besides all that, it saves me a TON of time and work not doing the crafts that are never really appreciated by the parents anyway.