There are two primary poles to the Christian liturgical calendar -- Christmas (marking the birth of Jesus) and Easter (marking the resurrection of the crucified one). Each of these poles include events beyond the birth and the resurrection, but they are the alpha and omega points of the calendar, and if we are willing they can shape our lives.
Sr. Joan Chittister is clear that the liturgical year -- indeed, the Christian faith -- turns on the celebration of Easter, the oldest of all Christian observances. As she notes in her book, The Liturgical Year, before there were any other celebrations Christians viewed the Sunday observance as a Little Easter. It was only later that they decided to make one Sunday of the year the apex of their celebrations. That said, the calendar contains more than one observance, and as such it helps form our lives (if we're willing).
Sr. Joan writes:
The Liturgical year, then, is a panoply, an array of events designed to shape us into being what we say we are -- followers of Jesus, disciples of Christ, the Christian community. It is a yearlong sojourn through the life of Christ to that ultimate point of self-giving, to that last breath of teaching, to that total surrender to the will of God, to that glorious new life that comes when we put this one at its service. (pp. 25-26).
She continues by pointing out that the church year "is month after month, every year of our lives, being taken back to the empty cross and the empty tomb, one way or another, in order to shape our own life in the light of them. It is those moments that reiterate the core of the faith" (p. 26).