Kala Xristougenna

 St. Nicholas is important in Greece as the patron saint of sailors. According to Greek tradition, his clothes are drenched with brine, his beard drips with seawater, and his face is covered with perspiration because he has been working hard against the waves to reach sinking ships and rescue them from the angry sea. Greek ships never leave port without some sort of St. Nicholas icon on board. To members of the Eastern Orthodox Church, as are most Greek Christians, Christmas ranks second to Easter in the roster of important holidays. Yet there are a number of unique customs associated with Christmas that are uniquely Greek. On Christmas Eve, village children travel from house to house offering good wishes and singing kalanda, the equivalent of carols. Often the songs are accompanied by small metal triangles and little clay drums. The children are frequently rewarded with sweets and dried fruits.
After 40 days of fasting, the Christmas feast is looked forward to with great anticipation by adults and children alike. Pigs are slaughtered and on almost every table are loaves of christopsomo ("Christ Bread"). This bread is made in large sweet loaves of various shapes and the crusts are engraved and decorated in some way that reflects the family's profession.
Christmas trees are not commonly used in Greece. In almost every home the main symbol of the season is a shallow wooden bowl with a piece of wire is suspended across the rim; from that hangs a sprig of basil wrapped around a wooden cross. A small amount of water is kept in the bowl to keep the basil alive and fresh. Once a day, a family member, usually the mother, dips the cross and basil into some holy water and uses it to sprinkle water in each room of the house. This ritual is believed to keep the Killantzaroi away from the house.
There are a number of beliefs connected with the Killantzaroi, which are a species of goblins or sprites who appear only during the 12-day period from Christmas to the Epiphany (January 6). These creatures are believed to emerge from the center of the earth and to slip into people's house through the chimney. More mischievous than actually evil, the Killantzaroi do things like extinguish fires, ride astride people's backs, braid horses' tails, and sour the milk. To further repel the undesirable sprites, the hearth is kept burning day and night throughout the twelve days.
Gifts are exchanged on St. Basil's Day (January 1). On this day the "renewal of waters" also takes place, a ritual in which all water jugs in the house are emptied and refilled with new "St. Basil's Water." The ceremony is often accompanied by offerings to the naiads, spirits of springs

 http://www.aglaiakremezi.com/articles/128/christmas-in-greece

Greek Traditional Recipes for Christmas