Christmas is an annual celebration which nominally commemorates the birth of Jesus Christ. In the Catholic and Protestant churches, it takes place on December 25th. It is held on the 7th January under the Orthodox Christian tradition.  The holiday is celebrated by people of different religions and cultures all around the world. It originated as a pagan holiday and Christianised to suit changing religious beliefs. However, it still retains significant pagan influences. Atheists are sometimes accused of hypocrisy when celebrating religious holidays.
Many churches consider Easter to be much more significant that Christmas. The nativity is not even mentioned in the Gospels of Mark and John, which indicates its original unimportance. The story of Jesus being born in Bethlehem is unlikely because the census pretext does not make any sense Luke 2:1-2 .
In early-to-mid 4th century, The Western Christian Church set the date of Christmas to December 25 as a means to rival existing solstice celebrations, and was later also adopted in the Eastern churches.
Natalis Invicti ("birthday of the unconquered one") was a festival celebrating the rebirth of the sun, Sol Invictus ("Invincible Sun"), the official sun god of the Roman Empire. Scholars argue that the festival was placed on the date of the winter solstice as the sun would seemingly reverse its retreat and thereby prove itself unconquered. Early Christian writers connected the rebirth of the sun with the birth of Jesus Christ, and the festival is believed to be responsible for the date of Christmas.
Saturnalia is an ancient Roman celebration of Saturn, the youngest of the Titans and father of the gods in Roman and Greek mythology. While originally only celebrated for a day, it grew to a week-long celebration starting at December 17 and ending at December 23. Besides the public rites involved in the festival, there were also a series of holidays and customs celebrated privately. The celebrations included a school holiday, gift-giving and a special market.
Yule is a Germanic pagan winter festival taking place on December 25. The festival was later absorbed into the Christian festival of Christmas. Customs such as the Yule log, the Yule goat, the Christmas ham, wassailing (caroling), etc. all come from Yule.
A Christmas tree is a evergreen coniferous tree which is brought into the home and decorated with lights and ornaments during the Christmas season. The historical origins of erecting a decorated Christmas tree can be traced back to 15th century Livonia (present-day Estonia and Latvia), although similar practices can be found prior to that. During Saturnalia, the Romans would decorate their homes with evergreen shrubs and dress up living trees with metals and idols of Bacchus, the god of wine and intoxication . Some Christians feel that the practice of decorating Christmas trees is too similar to the pagan custom, citing Jeremiah 10:1-5 as reason to condemn both:
- ""Hear what the LORD says to you, people of Israel. This is what the LORD says: “Do not learn the ways of the nations or be terrified by signs in the heavens, though the nations are terrified by them. For the practices of the peoples are worthless; they cut a tree out of the forest, and a craftsman shapes it with his chisel. They adorn it with silver and gold; they fasten it with hammer and nails so it will not totter. Like a scarecrow in a cucumber field, their idols cannot speak; they must be carried because they cannot walk. Do not fear them; they can do no harm nor can they do any good.”"
Despite Christmas being associated with the birth of Jesus Christ, there is no biblical passage or other evidence establishing Jesus's date of birth. While there is no established date for the birth of Jesus, the following passage from Luke 2:8-12 seem to suggest that he was born during the lambing season:
- "And there were shepherds living out in the fields nearby, keeping watch over their flocks at night. An angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were terrified. But the angel said to them, “Do not be afraid. I bring you good news that will cause great joy for all the people. Today in the town of David a Savior has been born to you; he is the Messiah, the Lord. This will be a sign to you: You will find a baby wrapped in cloths and lying in a manger.”"
The date of the 25th December was chosen to absorb and co-opt existing pagan festivals.
Mistletoe, holly, ivy
Mistletoe is a sacred plant in both Celtic and Viking mythology. Holly was used to repel evil spirits. Ivy was also used within pagan and Roman religion. Front door wreaths are based on the same traditions.  Their use was suppressed by Christian authorities for centuries but is considered generally acceptable in modern times, despite their pagan origins.  Their significance has even been reinterpreted to fit Christian beliefs. 
Santa Claus is probably based Dutch Sinterklaas celebration, revived in the United States and reimported back to Europe. Several elements of the festival have no Christian basis but have strong similarities with Odin of Norse mythology. It is likely that some pagan elements were adopted into the Sinterklaas festival.
War on Christmas
The term War on Christmas gained traction in the early 2000s, thanks to conservative commentators such as Fox News's Bill O'Reilly. The term is used to denote the alleged censorship of Christmas, and how the use of terms and phrases such as Xmas and Happy Holidays are, as Fox News host John Gibson puts it, a "liberal plot to ban the sacred Christmas holiday". Scientist and former White House senior policy analyst Jeff Schweitzer stated that "there is no war", and "Christians like Bill O'Reilly have declared war on religious freedom, demanding that the United States convert to a Christian nation", referring to their insistence that stores and the like should use language which is explicitly Christian.
The use of alternative terminology is sometimes encouraged in government departments and institutions, such as "seasons greetings" or even "Winterval". This is often motivated by the desire to be more inclusive to the people, many of whom are not Christians, but often is accused of "political correctness gone mad".
- "Clearly there are some Christians who are concerned about whether they are free to talk about their faith in a respectful and appropriate way in the workplace. [...] There is, amongst some Christians - this isn't universal - a sense of being a little picked on or beleaguered. I think if you claim to be open-minded and liberal, why are you so frightened of religious expression? The joke with all of this is that most people of other faiths have absolutely no problem with anyone talking about their faith. It's the secularists that have a problem."
The backlash that these Christians fear is simply not being taken seriously. This is not persecution, since being taken seriously is not a right, but rather a false Christian victimhood. Apologists sometimes conflate this issue with issues surrounding workplace rights and religious clothing.
- Remember the sabbath day, to keep it holy - another day that Christians celebrate at the wrong time.