January 1st became the start of the year about half a century before Jesus was born. 25 of December is close to the winter solstice (around 22nd), and I suspec

January 1st became the start of the year about half a century before Jesus was born. 25 of December is close to the winter solstice (around 22nd), and I suspect it was ascribed to that day for astrological reasons; there are a few other astrological clues around that episode, most prominently, the Bethlehem Star.