Why do Christians need a calendar?

The Christian tradition includes a pattern for teaching important events in the life of Jesus every year. The year begins with Advent, the season of anticipating Jesus' birth. It concludes (usually late November) with Christ the King Sunday. One of the seasons in the life of Jesus is Lent, which ushers in the celebration of Easter.

Long ago church leaders wanted to make sure that their teachings covered all the important stories. They devised a calendar, prescribing certain Bible passages and stories that should be taught. You can find the current church calendar here. 

I have to admit that I don't know a lot about the calendar, but I do know that I need regular reminders. In the season of Lent, I need to remember my own mortality, need for the grace of God, and the great sacrificial love that Jesus gives to me.