R is for Resurrection, which is what Christmas also celebrates.

For many Christians and countless North Americans, the Christmas season has been reduced to a celebration of the "birth date" of Jesus or the more generic practice of good will, public charities and consumerist frenzy. But if we look at the history of "why" the Church started to celebrate the Christmas Cycle (why we have the seasons of Advent, Christmas and Epiphany on the liturgical calendar) we learn something very different. We see that the Christmas Cycle is a result of the Church's missionary efforts to turn a pagan celebration of the winter solstice into a "minor" celebration of the "paschal" mystery: that is, of the salvation won for us through the suffering, death and resurrection of Jesus Christ, which Christians have traditionally referred to as the new "Passover." Christmas, in other words, is a reshaped, mini-celebration of Easter; Advent is like a mini-Lent; and Epiphany is like a foreshadowing of Pentecost. Although the images and metaphors of the Easter and Christmas cycles differ, their goal is the same: Faith in the crucified and risen Christ. We may like to romanticize the birth of Jesus and celebrate Christmas in July, but what the tradition of the Church would have us do, by giving us Christmas, is celebrate our Easter hope in the dead of winter.

That the center of the Christian faith (and hence, of all Christian worship) is the fact of what God did in the death and resurrection of Jesus Christ is evident from earliest times. For instance, because of this fact the Church turned Sunday, the day Jesus rose from the dead, into its day of worship. This it did, amazingly enough, in spite of the biblical commandment about observing the Sabbath (rest) Day, a day that celebrated God's "creation." Christians observed Sundays in order to honor the "new creation" in Christ (2 Cor 5:17, Gal 6:15, Col 1:15), which supersedes the "old creation" referred to in Genesis. This principle, then, was applied wherever the Church went in mission. Whether the church went to the Jews or to the pagan nations, its one mission was to make the fact of the death and resurrection of Jesus Christ the center of any religious faith; and it is precisely on the basis of this missionary concern that the Christian calendar was formulated, including the observance of Christmas.

Given this missionary concern, there is little wonder why the first and chief celebration that the Church placed on its calendar of seasons was the Triduum, that three-day observance of Maundy Thursday, Good Friday and Easter Sunday. Nor is there any wonder why its celebration was designed to coincide with the Jewish Passover. This the Church did, not simply to mark the actual day of the event (after all, the date of Passover changes too, as does, therefore, Easter), but rather to highlight the meaning of the event (as "the new Passover" for all people) relative to the religious tradition in which it occurred, the "Jewish Passover." For many years, then, while Christianity remained primarily a Christ-confessing movement within Judaism, Sundays and the Easter Season were the only Christian celebrations.