An excellent recent movie that discusses the origins of many Christian traditions and the much older, extremely similar versions is "Religulous", by Bill Maher. He takes on a lot of the accepted thoughts and traditions of not just Christianity, but Judaism, Islam, and other major religions. It is a very interesting and thought-provoking movie. Warning--open mind required for viewing! :)
As mentioned by many, Christmas did not originate as a specifically Christian celebration. I do believe there is an old connection to the annual or seasonal rebirth of pagan deities, but when did it acquire its Christian overtones? So what I would be interested in learning is when and why it began to be documented as the official celebration of Christ’s birth.
Most "holy days" predate religion; As people began to study celestial events, rituals and some kind of priestly case evolved. Certainly prehistoric cultures knew about eclipses, equinoxes, and solstices. "Christ's Mass," supplanted Saturnalia in ancient Rome (http://ancienthistory.about.com/od/saturnalia/a/saturnalia.htm) which in turn has its origins in fetility rites and the marking of a new year by noting the winter solstice. What's fascinating is the layering of ritual upon ritual over the ages as each culture throws into the melting pot its concept of Christmas, and that has come to define the holiday we know.
In Western countries, there has been a Christian majority population. Holiday decorations are placed in commercial venues like stores, restaurants, and malls that are frequented by non-Christians as well. Add to that the television programs and radio stations, and you have a pervasive influence on the popular culture by Christmas.
As sensitivity to cultural diversity increases, the effort is made not to assume that everyone is Christian. Therefore, stores advertise “Holiday Greetings” instead of “Merry Christmas.” There is a backlash among many Christians against this trend, but I don’t think it’s necessarily bad. I think it’s thoughtful to take into account that fact that not everyone is Christian. It doesn’t diminish my own Christian belief for a clerk to say “Happy Holidays” to me instead of “Merry Christmas.”
Even without its religious significance, Christmas is a joyful holiday, a celebration of love and sharing. It is a time when we stop to think about those we love and appreciate and to express those feelings with cards and gifts. Christmas is also a time when we often think of those we love who are no longer with us and bless their memory. Christmas is a special time for many people in that memories of other Christmases are an important part of our lives, markers of time having gone by.
Many people do not know the religious symbolism of Christmas, even people who attend church. Christmas has become a time of family and friends with, of course, good food and gifts. It is part of our culture. So, people who are in that culture celebrate it. From this perspective, why would one not celebrate Christmas (assuming they share our culture) is an equally important question.
If you are asking why non-Christians celebrate Christmas, I would argue two things:
1. Christmas has become quite secular. Santa Claus is not really any kind of religious figure anymore, snowmen never were, lots of Christmas songs have no religious meaning. So it's just a big holiday that has no specific meaning.
2. Without its religious connotations, it's just fun and who's against that? There's gift giving and gift getting, parties, decorations. All of that is fun.
People are religious because of handed-down beliefs from before science. Before science you could only explain the world with 'god'. Early religious leaders said God 'told' them all the rules about social behaviour and 'good' people MUST follow the rules. Every society developed a different 'special book' of religious rules.
Years ago, people were so worried about sickness, war, earthquakes, floods, hell and so on, they were very serious about religious rules. They taught their children to NEVER question them. If people questioned the rules, they were burnt alive.
You were taught these handed-down rules.
Then science started.
Christmas is not originally a Christian festival. It was absorbed from other religions. Religion behaves like a business and takesover older religious beliefs. Mary used to be a pagan godess. Christmas used to be a Pagan festival. Now, modern Christmas is a capitalist festival. It has ceased to be a Christian festival. Maybe good things have been lost, but ultimately, Christianity is a bunch of old pre-scientific rules that are not relevant to us.
Christmas is a patch-work quilt. It changes over time. In fact, our idea of Christmas mostly comes from Charles Dickens' book, 'Christmas Carol'. Try to find a reference in your Bible to a Christmas tree! It is a pagan belief. Your Christmas tree is an ancient pagan religious rule. It has been handed down to us.
But people used to think that tree was very holy.
why people are riligious?
Do you think the evergreen Christmas Tree is part of Christianity? (Or Easter Eggs at Easter for that matter) That tree is a pagan symbol. And it is part of an old, old tradition of bringing something living into your house during the deep mid-winter.
Christmas is much older than Christianity. The mid-winter festival has roots in Pagan religion and Roman religion. It is a multi-faith creation.
As I observe things in India, many people celebrate Christmas and many other so called religious festivals more for enjoyment and fun rather than because of any religious convictions. Many people organize and attend Christmas parties, but do not go to the church. Such people include many Christians also. Similarly there are so called Hindu festivals, which are celebrated by people following other faiths just for the fun and enjoyment.
In addition, to this there are also non-Christians who believe in Jesus Christ and celebrate Christmas as birthday of Jesus Christ. Hindus in particular are not prevented by their religion from worshipping any great soul. For example, people associated with a temple of lord Krishna, which I visit regularly, consider Jesus Christ as one of the many incarnations of supreme God, and celebrate Christmas by singing Christmas carols in the temple.