Most Christmas stories start with a journey to Bethlehem. This one starts with a calendar.

Roman mosaic portraying Jesus Christ as Sol Invictus.

As the Earth orbits the sun, there are periodic days where the day and the night have the same length. These are called equinoxes, and they occur every spring around the 20th or 21st of March, and every fall around the 22nd or 23rd of September. As winter approaches, the night gets longer and the days get shorter, until we reach a date with the shortest day and the longest night of the year. This is the winter solstice, and it occurs on December 21st in 2008 (except in the southern hemisphere, where it’s the summer solstice).

The solstices and equinoxes were quite important to ancient calendars, especially to the Roman calendar, where the solstice and equinox marked important feast days.

Prior to the reign of Julius Caesar, the Roman calendar was a mess. It consisted of years of 355 days, with some years having an extra month to make 378 days to balance things out. By the time Caesar declared a new calendar of 365 days, the previous calendar was so out of balance that the year 45 BC had to be 445 days long!

In the Julian calendar, the winter solstice was on December 25th. It remained there on the calendar until the Gregorian calendar was introduced in 1582 and the date was adjusted to December 21st.

An incredible variety of cultures hold celebrations on or around the winter solstice. As the day when the darkness of night finally begins to shorten and the light of day slowly starts to lengthen, it is a day rife with symbolic importance.

The Romans celebrated the festival of Saturnalia from December 17th to the 23rd. During that time, slaves and masters switched roles, with the masters serving dinner to the slaves. People also exchanged small presents, which could be the origin of Christmas gifts.

The celebration of the 25th of December came later, as part of the cult of Mithras and the worship of the Sun-God, Sol. Around 271 CE, the Roman Emperor Aurelian made Sol the premier God of the Empire. He may have dedicated the solstice as Sol Invictus, the day of the Unconquered Sun, although references to it do not appear until later.

The cult of Mithras was also powerful at that time. Since Mithraism was a mystery cult, required initiation to secret rituals, not much is clearly known. Mithras first appeared as an angel (more or less) in Zoroastrianism, where he was a protector of truth and divinity of light. Over time, he developed his own following. Several sources list the birth of Mithras as December 25th. On top of that, he was said to have been born of a virgin.

Mithras was not the only deity to be born on the winter solstice. Osiris, Adonis, Sol, Saturn, Crishna (Vishnu), Horus, Hercules, Dionysus (Bacchus), Tammuz, Indra, Buddha were all said to be born on December 25th.

It should be noted that the early Christians did not celebrate Christmas.

In 245, the theologian Origen of Alexandria stated that, “only sinners (like Pharaoh and Herod)” celebrated their birthdays. In 303, Christian writer Arnobius ridiculed the idea of celebrating the birthdays of gods, which suggests that Christmas was not yet a feast at this time.

The feast did not gain in popularity until around 400 CE. By that time, Christianity had become the official religion of the Roman Empire. It is not surprising that they selected a date that already had powerful religions implications and placed their own holiday on top of it.

That is not the only connection between Sun worship and Christianity. Halos appear in Roman art as the sign of the sun. They were adopted into Christianity as a sign of divinity.

There are other traditions that have been incorporated into the Christian holiday of Christmas. The Yule log is far from biblical; it has its origins in the Germanic celebrations of the winter solstice. Santa Claus, Christmas trees, presents, mistletoe and a host of other rituals were adopted from other religions or traditions.

Christianity is a syncretic religion, meaning that it borrows and mixes rituals and beliefs from other religions into their own. Christianity has taken ideas from Judaism, Zoroastrianism, Mithraism, Greek and Roman worship, pagan beliefs, and a host of others too long to delve into here.

As part of the movement from an underground faith to the religious structure that would dominate Europe for the next thousand years (and plunge it into the Dark Ages), early Christians took the date of the Roman holiday of Sol Invictus, the winter solstice, and made it their own.

So the next time someone scoffs at the political correctness of Happy Holidays, tell them you agree with them wholeheartedly.

And wish them a Happy Sol Invictus.