The world is telling a story of life that ends in death; the Church is telling the story of her Lord, a story of death that ends in life.
So the calendar of the Church is arranged to tell the story of Jesus Christ. There are two halves to the year, the Semester of the Lord and the Semester of the Church. In the first half, the Semester of the Lord, she focuses on a semi-chronological account of the life, death, and resurrection of Jesus. (She readily admits, however, that chronology is not her forte, beginning the year with Jesus' entry into Jerusalem.) The year begins with Advent, the season of anticipation for the “coming” of Jesus. This season anticipates both His coming at Christmas and also His coming once-and-for-all at His return. Advent has both a preparatory as well as a penitential mood to it. Then follows Christmas, always on December 25th. The Season of Christmas continues until the season of Epiphany. Epiphany is actually an older celebration than Christmas (second only to Easter) that celebrates the manifestation of Jesus as both God and man. Epiphany is also when we celebrate the Magi (who represent all nations) coming to visit Jesus.
Throughout these seasons, we celebrate significant events in the life of Jesus. 8 days after His birth, He was circumcised and given His Name (merely by accident this coincides with the world's New Year). During Epiphany, we celebrate our Lord’s Baptism as well as His first miracle. Epiphany ends with the Festival of the Transfiguration, the manifestation of Jesus’ glory to His disciples.
The three weeks before Lent are a mini-season (Gesima-tide) designed to prepare us for Lent. Lent, a season of fasting and repentance, focuses our attention on the coming Passion of Jesus. The last two weeks of Lent are Passiontide, when the fasting increases and the mood becomes even more somber. Passiontide and Lent culminate in Holy Week, the week when the Church tells the story of the last week of the life of her Lord Jesus.
Lent—with its fasting and weeping—ends on Easter (technically on Easter Eve, the Easter Vigil), the season when the Church proclaims the Resurrection of Her Lord and the promise of eternal life for all who have faith in Him for forgiveness. A season full of unbridled joy, Easter lasts 7 weeks. Fourty days after His Resurrection, Jesus ascended; so, forty days after Easter, at the Ascension of the Lord, the Church celebrates the fact that human flesh now dwells at the right hand of God the Father, in the God-man Jesus. Fifty days after Easter is Pentecost, an Old Testament harvest festival that now celebrates the “harvest” of believers for Christ. Marking the outpouring of the Holy Spirit onto the disciples, Pentecost is also the birthday of the Church.
Pentecost marks the transition from the Semester of the Lord to the Semester of the Church, which begins with Trinity Sunday. This second half of the Church Year focuses on How the Lord grows His Church through His gifts of Word and Sacrament. Trinity season culminates with a 3-week season at the end (akin to the 3-week season that prepares us for Lent) that prepares us for Advent and the start of another Church Year. Then the cycle begins all over again, as the Church never ceases to proclaim the story of her Lord, the story of salvation.