This is another American eccentricity I’ve noticed since coming to the USA for my post-doc. Many atheists especially seem to “campaign” on Internet forums for the purpose of enlightening Christians to pagan origins for Christmas observance and traditions. (One gets the impression that they’ve recently learned some “fun facts” and are determined to share them with everyone they encounter.) But why is there any assumption that the pagan origins are some sort of “smoking gun”? Why do they assume that anyone would much care?