Why Jehovah's servants doubt that Christ was ever part of the yuletide festivities:The Watchtower Society's commentary.

What Does the Bible Say About Christmas?
The Bible’s answer

The Bible does not give the date of Jesus’ birth, nor does it say that we should celebrate his birthday. As McClintock and Strong’s Cyclopedia states: “The observance of Christmas is not of divine appointment, nor is it of NT [New Testament] origin.”

Instead, an examination of the history of Christmas exposes its roots in pagan religious rites. The Bible shows that we offend God if we try to worship him in a way that he does not approve of.—Exodus 32:5-7.

History of Christmas customs

Celebrating Jesus’ birthday: “The early Christians did not celebrate [Jesus’] birth because they considered the celebration of anyone’s birth to be a pagan custom.”—The World Book Encyclopedia.

December 25: There is no proof that Jesus was born on that date. Church leaders likely chose this date to coincide with pagan festivals held on or around the winter solstice.

Gift-giving, feasting, partying: The Encyclopedia Americana says: “Saturnalia, a Roman feast celebrated in mid-December, provided the model for many of the merry-making customs of Christmas. From this celebration, for example, were derived the elaborate feasting, the giving of gifts, and the burning of candles.” The Encyclopædia Britannica notes that “all work and business were suspended” during Saturnalia.

Christmas lights: According to The Encyclopedia of Religion, Europeans decorated their homes “with lights and evergreens of all kinds” to celebrate the winter solstice and to combat evil spirits.

Mistletoe, holly: “The Druids ascribed magical properties to the mistletoe in particular. The evergreen holly was worshiped as a promise of the sun’s return.”—The Encyclopedia Americana.

Christmas tree: “Tree worship, common among the pagan Europeans, survived after their conversion to Christianity.” One of the ways in which tree worship survived is in the custom of “placing a Yule tree at an entrance or inside the house in the midwinter holidays.”—Encyclopædia Britannica.

OR From history.com:

AN ANCIENT HOLIDAY:The middle of winter has long been a time of celebration around the world. Centuries before the arrival of the man called Jesus, early Europeans celebrated light and birth in the darkest days of winter. Many peoples rejoiced during the winter solstice, when the worst of the winter was behind them and they could look forward to longer days and extended hours of sunlight.

In Scandinavia, the Norse celebrated Yule from December 21, the winter solstice, through January. In recognition of the return of the sun, fathers and sons would bring home large logs, which they would set on fire. The people would feast until the log burned out, which could take as many as 12 days. The Norse believed that each spark from the fire represented a new pig or calf that would be born during the coming year.

The end of December was a perfect time for celebration in most areas of Europe. At that time of year, most cattle were slaughtered so they would not have to be fed during the winter. For many, it was the only time of year when they had a supply of fresh meat. In addition, most wine and beer made during the year was finally fermented and ready for drinking.

In Germany, people honored the pagan god Oden during the mid-winter holiday. Germans were terrified of Oden, as they believed he made nocturnal flights through the sky to observe his people, and then decide who would prosper or perish. Because of his presence, many people chose to stay inside.

SATURNALIA:In Rome, where winters were not as harsh as those in the far north, Saturnalia—a holiday in honor of Saturn, the god of agriculture—was celebrated. Beginning in the week leading up to the winter solstice and continuing for a full month, Saturnalia was a hedonistic time, when food and drink were plentiful and the normal Roman social order was turned upside down. For a month, slaves would become masters. Peasants were in command of the city. Business and schools were closed so that everyone could join in the fun.

Also around the time of the winter solstice, Romans observed Juvenalia, a feast honoring the children of Rome. In addition, members of the upper classes often celebrated the birthday of Mithra, the god of the unconquerable sun, on December 25. It was believed that Mithra, an infant god, was born of a rock. For some Romans, Mithra’s birthday was the most sacred day of the year.

In the early years of Christianity, Easter was the main holiday; the birth of Jesus was not celebrated. In the fourth century, church officials decided to institute the birth of Jesus as a holiday. Unfortunately, the Bible does not mention date for his birth (a fact Puritans later pointed out in order to deny the legitimacy of the celebration). Although some evidence suggests that his birth may have occurred in the spring (why would shepherds be herding in the middle of winter?), Pope Julius I chose December 25. It is commonly believed that the church chose this date in an effort to adopt and absorb the traditions of the pagan Saturnalia festival. First called the Feast of the Nativity, the custom spread to Egypt by 432 and to England by the end of the sixth century. By the end of the eighth century, the celebration of Christmas had spread all the way to Scandinavia. Today, in the Greek and Russian orthodox churches, Christmas is celebrated 13 days after the 25th, which is also referred to as the Epiphany or Three Kings Day. This is the day it is believed that the three wise men finally found Jesus in the manger.

By holding Christmas at the same time as traditional winter solstice festivals, church leaders increased the chances that Christmas would be popularly embraced, but gave up the ability to dictate how it was celebrated. By the Middle Ages, Christianity had, for the most part, replaced pagan religion. On Christmas, believers attended church, then celebrated raucously in a drunken, carnival-like atmosphere similar to today’s Mardi Gras. Each year, a beggar or student would be crowned the “lord of misrule” and eager celebrants played the part of his subjects. The poor would go to the houses of the rich and demand their best food and drink. If owners failed to comply, their visitors would most likely terrorize them with mischief. Christmas became the time of year when the upper classes could repay their real or imagined “debt” to society by entertaining less fortunate citizens.