There seems to be something in our nature that makes us celebrate anniversaries - whether wedding anniversaries, birthdays, or yearly festivals like the first of August. And in our church calendar, too, we work on a yearly cycle (even if our readings now follow a three-yearly pattern.)
The church's year starts on Advent Sunday - that's the Sunday nearest to St Andrew's Day, the thirtieth of November. (You may wonder why St Andrew comes into it - really it's to make sure there are always four "Sundays in Advent" before Christmas.) It passes through Christmas and Epiphany, and then through Candlemas into a time of preparation for Lent. Lent culminates in the remembrance of Good Friday, and the joy of Easter.
Easter is the high-point of the church's year, with the Ascension and Pentecost (Whitsun) following on the fortieth and fiftieth day. And then the church reverts to what is called "Ordinary Time", ending with All Saints' Day and a time of preparation for Advent.
On the way, there are numerous other festivals. Some of them have to do with Jesus' life - his naming and circumcision on 1 January, the eighth day of Christmas; the angel's annunciation to Mary of his conception, on 25 March; the remembering of his transfiguration on 6 August. Others began as local festivals to commemorate local events and local saints, and some of these have spread, sometimes losing something of their religious quality on the way (like the celebration of Nicholas of Myra on 6 December, or Valentine of Terni on 14 February - though in the Anglican church, 14 February is the day we celebrate Cyril and Methodius, ninth century missionaries to the Slavs).
The dates of many of these festivals often had more to do with pre-existing customs than with anything else. Christmas is a good example. We do not know when Jesus was born, and nobody has yet come up with a date that fits a Roman census, a jealous Herod, a Syrian governor and a group of startled shepherds. About 200 AD, Clement of Alexandria suggested 20 May as a likely date. 25 December is a very unlikely date, and the earliest we hear of a church festival then was in 336 AD in Rome.
Having Christmas in December was a good way of stressing and reinforcing the church's joy at the birth of Jesus, the Sun of Righteousness, over against the pagan and secular festivals taking place at the same time to celebrate the change of the season and the lengthening days. This doesn't mean that Christmas is a pagan festival - just that the pagan rejoicing and merriment for the "Birth of the Undefeated Sun" has been taken over completely by something both truer and more joyful! May we all share in this joy with glad and open hearts!
HD