The term Christian Church when used as a proper noun usually refers to the whole Christian religious tradition throughout history. When used in this way the term does not refer to a particular denomination or to a building. However, the majority of Christians belong to groups that consider themselves to be the one true church. The three largest such groups are the Roman Catholic Church, the Eastern Orthodox Church and the Oriental Orthodox communion.
Thus, some Christians identify the Christian Church with a visible structure (the view of the Roman Catholic, Eastern Orthodox and Oriental Orthodox churches), while others understand it as an invisible reality not identified with any earthly structure (the general Protestant view) and others equate it with particular groups that share certain essential elements of doctrine and practice though divided on other points of doctrine and government (such as the branch theory as taught by some Anglicans).
The Christmas season is celebrated in different ways around the world, varying by country and region. Elements common to many areas of the world include the lighting of Christmas trees, the hanging of wreaths, Christmas stockings, candy canes, and the creation of Nativity scenes depicting the birth of Jesus Christ. Christmas carols may be sung and stories told about such figures as the Baby Jesus, St Nicholas, Santa Claus, Father Christmas, Christkindl or Grandfather Frost. The sending of Christmas cards, the exchange of Christmastime greetings, observance of fasting and/or special religious observances such as a midnight Mass or Vespers on Christmas Eve, the burning of a Yule log, and the giving and receiving of presents. Along with Easter, Christmas time is one of the most important periods on the Christian calendar, and is often closely connected to other holidays at this time of year, such as Advent, the Feast of the Immaculate Conception, St. Nicholas Day, St. Stephen's Day, New Year's, and the Feast of the Epiphany.
Christmas Eve is the evening or entire day before Christmas Day, the widely celebrated annual holiday. It occurs on December 24 in the Western Christian Church, and is considered one of the most culturally significant celebrations in Christendom and the Western world, where it is widely observed as a full or partial holiday in anticipation of Christmas Day.
One reason celebrations occur on Christmas Eve is that the traditional Christian liturgical day starts at sunset, an inheritance from Jewish tradition. This practice is based on the story of Creation in the Book of Genesis: "And there was evening, and there was morning – the first day." This structure for the liturgical day is followed for all feast days throughout the year in the Eastern rite and is retained for Christmas (as well as for Sundays and other major festivals) in the West, where the liturgical day ordinarily begins at midnight. Many churches still ring their church bells and hold prayers in the evening before holidays; for example, the Nordic Lutheran churches. In some languages, such as the Scandinavian, Christmas Eve is simply referred to as "Christmas Evening".