The Kinks' "Father Christmas" works for me. "Father Christmas, give us some money/Don't mess around with those silly toys/We'll beat you up if you don't hand it over/We want your bread so don't make us annoyed"
I've been an atheist most of my life. I don't tell people about it, and I don't lose my shit when a group of Christians enter a room, loudly proclaiming their beliefs and telling me I'm going to hell. I just ignore them, because IDGAF.