wouldn't it really suck if the world WAS flat?
According to author Dan Brown in The DaVinci Code
The Bible makes no mention of Christ being born in December (in fact, I think he wrote something about the Biblical version has his birth in March?) but the pre-Christian celebration of 'SOL INVICTA' took place about DECEMBER 25th.
Sol Invicta, or Victorious Sun, refers to the time of years when it was becoming noticeable that the days were again increasing in length.
Many of these Pre-Christian Pagan Events were co-opted into Christianity.
The most commonly accepted image of God (Old white man with white hair and white beard) was simply the accepted image of Zeus/Jove)
and much of the Nativity Story had been part of religious creation stories for a thousand years before the birth of Christianity.
Zoroastrianism (Ahura Mazda) has a virgin birth, three wise men (the Magi) following a star and many similar events.