Christmas in America is really about the Winter Solstice. Americans are quite out of touch with Nature, the reason for seasonal changes, and the importance of the Solstices. What is the common denominator that has all these religions vying for "their most important day" on or near Dec. 25th? It is the Winter Solstice. Humans have celebrated the Winter Solstice for millennia. It could be argued that the Winter Solstice is the single most influential and important event of the year. We're hardwired to appreciate the end of short days and that day's lengthening to more sun and longer days. Many holidays conform to this time and celebrate on or near Dec 25th. The Winter Solstice, Dec 21, and the Summer Solstice, June 21, are the most dramatic of the Natural Holidays. Many, many candles are lit on this shortest of nights, in many religions, in many countries, and in many customs outside of Christianity.
The date of Christmas, December 25, was borrowed from another religion. At the time Christmas was created in AD 336, Mithraism was very popular. The early Christian church had gotten tired of their futile efforts to stop people celebrating the solstice and the birthday of Mithras, the Persian sun god. Mithras' birthday was December 25. So Pope Julius I decided to make Jesus' official birthday coincide with Mithras' birthday. All honest Biblical scholars (Christian and non Christian) admit and agree that Jesus was not born on Dec. 25. Dec 25 became the consensus date, and a logical way to assimilate the pagan, and Earth based Winter Solstice gatherings into the Christian religion. The writings in the Bible contradict the creation of Christmas on Dec 25 because of weather. The shepherds and their flocks were not "in the fields;" they were in shelter; no one travelled in mid winter (it was too hard), and a manger at night on Dec 25 in Bethlehem was very cold. The Holy Family's whole journey, if at all, started at another time of the year.
Since 336 AD in Christian Rome, we have had Dec 25 designated as Jesus' birthday. Before that date, there were many myths very similar to the Biblical account of Jesus' life that circulated in the Middle East for hundreds of years before Jesus. In these myths, the hero was always born near the Winter Solstice. Roman 'Attis' was a son of the virgin Nana, born on Dec 25 and died on Mar 25 (Spring Equinox) after being crucified on a tree. Greek 'Dionysus', Persian (and Roman) 'Mithra' and Egyptian 'Osiris' have been worshipped since Neolithic times and were all born on Dec 25. Other pagan gods whose "birthday' was on Dec. 25 are Horus, Attis, Dionysus, Tammuz, Hercules, Perseus, Helios. Bacchus, Apollo, Jupiter and Sol Invictus.
According to most sensible researchers, the date of Jesus' birth is April 17, 6BCE. The Urantia Book says Aug 21, 7 BCE.
http://www.opednews.com/articles/How-the-Winter-Solstice-wa-by-Douglas-Morrison-101222-25.html