As Christians begin another sacred church year, realize that for centuries before Christ the Jews had their sacred “church year”. God initiated this Jewish ecclesial calendar when at the Passover 
event He directed, “This month shall be the beginning of months for you; it is to be the first month of the year to you.” (Ex. 12:2). This new “first month” was the seventh month of the secular year. So the Jews in effect celebrated two “New Year’s Days”: The sacred New Year was initiated by the celebration of the Passover, and the secular New Year began with the celebration of Rosh Hashanah, which itself marked the beginning of highly sacred events in the seventh month of the Jewish church year. Interestingly every seven months the Jews celebrated New Year’s Day, alternating with the sacred New Year’s Day and the secular New Year’s Day.
Some believe Christianity should begin its sacred New Year with Holy Week. Instead, most in the U.S. begin it with Advent, the penitential time preparing for the celebration of Christmas. The traditional Gospel for the First Sunday in Advent is usually a Palm Sunday reading—a reading connecting Christ’s work to that of the Passover. Psalm Sunday was the day when many at the time of Jesus—imitating that initial Passover—selected their Passover Lamb to be sacrificed at the Temple later that week. On that first Palm Sunday God thus “selected” His Beloved Son to be the eternal Passover Lamb, so by His death, death would truly pass over mankind in resurrection.
Jesus was riding into Jerusalem to fulfill His life’s purpose—to die as our Passover Lamb. This was why He was born, and thus His birth, which we will soon celebrate, is directly associated with His sacrifice as our Passover Lamb. How appropriate that we begin Advent with this Passover-related reading!
Shepherds were among the first to see the newborn Christ. These shepherds, tending their sheep only a few miles from Jerusalem, had as their primary occupation the raising of sheep for Jewish sacrifice—primarily sheep for the Jewish Passover celebration. The Jewish historian Josephus states that at a single Passover at the time of Christ 250,000 Passover lambs were slain at the temple. What a grand event and a grand feast this was for God’s people! But God’s ultimate Passover Lamb and His ultimate feast were, uniquely on Palm Sunday, arriving in Jesus of Nazareth.
Thus the Passover Lamb marks the beginning of both the Jewish Church Year and—because of the Palm Sunday reading and because Jesus is THE Passover Lamb—the beginning of the Christian Church Year. On that first Palm Sunday the Jews were preparing for numerous unwilling lambs to be sacrificed. For Christianity that Palm Sunday beheld the willing Lamb of God who takes away the sin of the world. Now we regularly (often weekly) celebrate our Passover feast: “Christ our Passover Lamb has been sacrificed. Let us therefore celebrate the feast…” (1 Cor. 5:7b,8a)