It’s easy to see why Jesus impossibly could have been born on December 25^th. Luke tells us that there were ‘shepherds abiding in the field, keeping watch over their flock by night’ (2:8-12). That couldn't have been in the rainy, chilly winter season.

In those days, it was custom for shepherds to bring out their sheep in spring and return home at the first rainfall in October or November. “It is the rainy season; so we cannot stand outside”, a crowd of Jews tells the prophet Ezra in the Book of Ezra (10:13).

In the first centuries after Jesus lived, most people believed that Jesus had been born on March 25^th, the day of the spring equinox. Other churches celebrated Jesus’ birthday in January or May, or chose not to celebrate it at all.

On December 25^th, our current Christmas, people celebrated a very different religious feast. December 25^th is known as the Winter Solstice, an astronomically important day. To many ancient religions, it was a holy party day, signifying the rebirth of the sun.

That's why people in the Roman Empire celebrated a hotch-potch of feasts on December 25^th, like the birthday of the Persian sun god Mithras and the rebirth of the Syrian sun god Elah Gabal. In Scandinavia, people celebrated Yule, a feast in honor of Odin.

That was until Christianity became the official state religion of the Roman Empire in AD 312. Obviously, the Roman rulers couldn't tolerate the pagan feasts anymore. Turning December 25th into a Christian party seemed like the best way to do it.

And so they did.

In AD 354, bishop Liberins of Rome commanded Jesus’ birthday party to be celebrated on December 25^th from now on. And forty years later, emperor Flavius Theodosius declared all pagan feasts that hadn’t been ‘Christianized’ yet illegal.

That’s how 400 years after Jesus died, December 25^th suddenly became a Christian party!

Still, much of the content is still pagan. After all, Jesus wasn't hung in a Christmas tree, or something.

Rather, the Christmas tree reminds of ancient tree worship, the rich meals echo the wild eating and drinking parties from ancient, pagan times and scholars have pointed out that even Santa still has elements of Odin.