A holiday that evolved into a global cultural celebration

Christmas is a Christian holiday that observes the birth of Jesus.

- BY LUIS ANDRES HENAO

SIA KAMBOU AFP/Getty Images SANTA CLAUS looks on as customers shop for decorative garlands in Abidjan, Côte d'Ivoire, on Tuesday.

But did you know that the earliest followers of Jesus did not annually commemorate his birth? Or that Santa Claus is inspired by the acts of kindness of a 4th century Christian saint? Have you heard about the modern-day Japanese tradition of eating Kentucky Fried Chicken on Christmas?

Since the early 20th century, Christmas has evolved from a religious holiday to a hugely popular cultural holiday observed by Christian and secular people across the globe who gather with families, exchange gifts and cards and decorate trees.

Origins and early history of Christmas

Early followers of Jesus did not annually commemorate his birth.

The story of the birth of Jesus appears only in two of the four Gospels of the New Testament: Matthew and Luke. They provide different details, though both say Jesus was born in Bethlehem.

The exact day, month and even year of Jesus's birth are unknown, said Christine Shepardson, a professor at the University of Tennessee who studies early Christianity.

The tradition of celebrating Jesus' birth on Dec. 25, she said, only emerged in the fourth 4th century.

"It's hard to overemphasize how important the 4th century is for constructing Christianity as we experience it in our world today," Shepardson said. It was then, under Emperor Constantine, that Christians began the practice of gathering at churches instead of meeting at homes.

Some theories say the date coincides with existing pagan winter solstice festivals, including the Roman celebration of Sol Invictus, or the "Unconquered Sun," on Dec. 25.

Rowdy medieval street festivities