I recall being taught that one reason Washington attacked on Christmas was specifically because (English) American colonists didn't celebrate the holiday. The German Hessian mercenaries did, though, and so would be hung over and vulnerable when Washington and his army made their surprise attack. In other words, at the time of the Revolution Christmas was unAmerican.There is also some discussion of how our so-called "religious" holidays at this time of year are for the most part usurpations of previously-existing pagan holidays around the solstice, with their symbologies and traditions left largely intact, but with a new narrative superposed.
So again, axial tilt is the reason for the season, but whatever it is you care to celebrate during these shortest days of the year, it's all good as far as I'm concerned. Enjoy the season and the longer days to come.