I've always found the connection between Winter Solstice and the creation of the Christian holiday of Christmas to be a rather enlightening one. The liturgical year of the church was based around existing holidays and pagan festivals, for political reasons, in much the same way as overtly pagan statues of the Black Virgin became assimilated, at least superficially, to the cultus of the Blessed Virgin Mary and minor powers of the pantheons became assigned to the various Saints.
The Signs, Dates and Times
The date, December 25th, wasn't always fixed as the date of the birth of Jesus, either. Actually, Eastern Orthodoxy celebrated the birth of Messiah on January 6th, the date which became known as Epiphany (epiphaneia, to appear). Jesus, the Light of the World, replaced the Sol Invictus of the Mithraic mysteries, and the Nativity of Christ replaced the festival of popular culture only after Roman Christianity became dominant in about the 4th century.
Initially, only the Passion of Holy Week and its climax in Easter were widely celebrated. The liturgical year evolved in time as Roman Catholicism came to prominence, great wealth, and political power. Originally, the festival which became Christmas was of course held on the date approximating the Winter Solstice. By the 4th century, the dates of December 25th and January 6th had become widespread. The Epiphany commemorated the birth and baptism of Jesus as well as his adoration by the Magi. Christmas as we know it seems to have begun in Rome with Pope Liberius, in 354.
Winter Solstice provides an interesting analogy through its association with the birth of the Christ-child. The solstice, the entry of the sun into Capricorn (at least for a few years), marks the shortest day of the year, the day when the sun shines upon the earth for the least time and all seems lost, doomed to the eternal snows and ice of perpetual Hel, to crystallization and death. From this day forward, the light overtakes the darkness, until eventually reaching equality of night and day at Spring Equinox (on which Easter is celebrated), and then gradually overcoming the darkness, until the Summer Solstice. Clever, eh?!
- Latourette, Stephen. A History of Christianity, Volume I: Beginnings to 1500. Harper Collins 1956,1975, pp. 205-210