Worship . . . is meant to celebrate the coming of Christ (Advent); the birth of Christ (Christmas); the manifestation of Christ as the light of the whole world (Epiphany); the impending death of Christ (Lent); the events of his last week (Holy Week); the resurrection (Easter); and the coming of the Holy Spirit (Pentecost). These are the kairos events for Christians that give meaning and significance to our day-to-day lives in the world.
-Robert Webber, Worship Is a Verb: Celebrating God’s Mighty Deeds of Salvation, Second Edition