Why is Christmas celebrated in the Winter, when by all accounts Christ was born around Sept 23rd? It aligned with a Hebrew Holiday, and the stars aligned in the exact manner proscribed.
The day of his birth was n known by early Christians at the time that His birth became a holy day so it was assigned and it has been tradition ever since. Do you expect that scientifically determining the probable date of his birth as something other than the traditional one means we should shift Christmas to another date? That would cause a split and atheists who put up trees on Dec25 and some Christian sects would shift but most would not and the Catholics would not nor the Orthodox, probably not even the Anglicans.