Today, being the last Sunday before All Saints Day, is the Feast of Christ the King. In the Ordinary Form, it has been moved to the last Sunday of the Liturgical Year, or right before Advent.
Pope Pius XI instituted the feast with the encyclical Quas Primas, issued on December 11, 1925. The encyclical discusses the Holy Year of 1925, which celebrated the 16th centenary of the Council of Nicea, and how the celebrations of that year underscored the need to accept Jesus as King and Ruler, as is done throughout scripture, and, up until then, in pious practice. The first paragraph explains:
IN THE FIRST ENCYCLICAL LETTER which We addressed at the beginning of Our Pontificate to the Bishops of the universal Church, We referred to the chief causes of the difficulties under which mankind was laboring. And We remember saying that these manifold evils in the world were due to the fact that the majority of men had thrust Jesus Christ and his holy law out of their lives; that these had no place either in private affairs or in politics: and we said further, that as long as individuals and states refused to submit to the rule of our Savior, there would be no really hopeful prospect of a lasting peace among nations. Men must look for the peace of Christ in the Kingdom of Christ; and that We promised to do as far as lay in Our power. In the Kingdom of Christ, that is, it seemed to Us that peace could not be more effectually restored nor fixed upon a firmer basis than through the restoration of the Empire of Our Lord. We were led in the meantime to indulge the hope of a brighter future at the sight of a more widespread and keener interest evinced in Christ and his Church, the one Source of Salvation, a sign that men who had formerly spurned the rule of our Redeemer and had exiled themselves from his kingdom were preparing, and even hastening, to return to the duty of obedience.
At least in part, Pope Pius is responding to world events and the gathering storm clouds that presage a return to war. He points at moral principles being purged from the public sphere as a troubling trend, especially as the Church is discounted as an authority and increasingly pushed out of public discourse. The answer is to recognize that all earthly rulers, in whatever sphere, derive their authority from Jesus, The King.
Quas Primas puts the feast at the end of October, to fall just before All Saints Day, in order to reflect that Jesus is a Heavenly King, and His court is in Heaven. Our goal is to join that court after our sojourn here on Earth, or at the end of time. In 1970, the feast was moved to the last Sunday of the Liturgical Year to further emphasize the eschatological nature of Jesus’ kingship. In a way, that move makes sense–end the year on a high note, and get a reminder that the baby who came at the first Christmas will come again in full majesty at the end of time. On the other hand, emphasizing the eschatological nature of Christ’s kingship gets away from the need to work to bring His kingdom to Earth now, in the way we live our lives every day. It almost glosses over the fact that Jesus is king (present tense), and makes it easy to settle into an attitude of “Jesus will be king (future) at the end of time…no need to amend my life now.” If we slide into that attitude, then we’ve missed the point that Pope Pius was making–the only way to rectify the many wrongs in the world is to recognize that Jesus is King, and we are his subjects. His law is not obscure, nor is his yoke heavy.
In short, by celebrating Christ the King, it’s a reminder that we’re under God’s law, not just in the future when He comes again, but now, every day, so that we can show the world the joys that await those who turn to Him.