Merry Christmas to everyone. I'm sick today and can't be with my family, but my daughter's there. She's pagan and I'm sure very miserable, but she'll survive.
I don't consider "Merry Christmas" an insult- it simply means I enjoy a time where people behave with more attention to others and cheer than at other times and I wish you part of that too. It would not matter that you don't share my religious beliefs- I still use this time of the year to let anyone know that I wish them good and joy. And I hope that there is some time when they can give me a boost of energy from their special times too.
BTW Happy "Holy-days" ie Happy Holidays will not work any better for an atheist than anything else.
May everyone find an island of peace and joy- no matter what boat you use to get there.