This past Sunday marked the beginning of the liturgical season of Advent, recognized by the majority of Christian churches in the world.  While many Christians participate in the season as a matter of course, there are some who may be skeptical of the value of observing Advent (or any season of the liturgical year).  Others may be curious about the observance, while others may be complacent.  Why observe Advent?  This series is intended as a defense of the observance of Advent and Christmas by Christians of all stripes.

Is Advent historical?

Yes, the observance of Advent is undeniably historical.  Advent (Latin for "coming" or "arrival") is the season of preparation for and anticipation of the feast of Christmas, commemorating Christ's birth.  Celebrations of Christ's birth existed from earliest times in the Church, eventually settling the date of observance on December 25.  (This date was circulating by at least AD 354, and was widely practiced in the Church, along with January 6 as an alternative date, by the end of that century.)  A season of preparation for the feast was likewise observed early.  St. Sidney of Poitiers and the Council of Sargossa both refer to fasts leading up to Epiphany (Jan 6) in the 4th century, which for some time was an alternate celebration for Christmas.  It can be assumed that wherever the practice of feasting on the day of commemoration of Christ's birth was established, a time of preparation for the feast would have shortly been established as well.  The homilies of St. Caesarius, Bishop of Arles, in the 6th century appear to be intended for the time of preparation prior to the observance of Christ's birth.  Advent observances are thought to have existed since at least the 4th century, then. 

Originally, Advent was observed as a time of fasting (in some places, equal to that of Lent, which was forty days) beginning in mid-November.  Anglicans, Lutherans, and Catholics have since relaxed the fasting rule, and Advent is generally observed in the West now as a festive time of anticipation.  In the Eastern Orthodox churches, however, it is still a time of fasting, known as the Nativity Fast, leading up to their observance of Christ's Nativity (birth) on January 6, the old alternative date.

Advent has been observed as a preparation time for Christmas nearly universally since earliest times in the Church.  Post-Reformation, some denominations eschewed the observance of Advent season along with most or all of the traditional liturgical year, but these were the minority.  Today in the West, Catholics, Anglicans, Lutherans, Methodists, and some Presbyterians still officially observe the season, along with a smattering of  evangelicals.  Other traditions, while retaining the celebration of Christmas, have neglected the observance of Advent.

For more info: Advent history (from churchyear.net) and more Advent history (from Catholic encyclopedia).

Part 2: Why Advent? Time matters.