The last Sunday in October is traditionally the Feast of Our Lord Jesus Christ the King.
The Lesson is taken from the Encyclical Letter of Pope Pius XI
Since the Holy Year hath provided more than one opportunity to enhance the glory of the kingdom of Christ, we deem it to be in the highest degree in keeping with our Apostolic office to accede to the prayers of many Cardinals, Bishops, and faithful, made known to us both individually and collectively, by closing this very Year with the insertion into the ecclesiastical liturgy of a special feast of Our Lord Jesus Christ the King. It is a long-standing and common custom to apply, in a symbolic sense, the title of King to Christ. That is to say, to refer to him as King because he hath surpassed and excelled every created being by virtue of his sublime perfection in all things. In this sense he is said to reign in the minds of men. By which is meant, not only that the keenness of his mind and the extent of his knowledge surpasseth the rest of mankind, but that he is himself the Truth ; and hence that from him the truth is to be discovered, and also obédiently received, by all mankind. Likewise he is said to reign in the wills of men. For in him not only is the human will in exact and precise accord with the holiness of the divine will, but also from him doth come to us the grace and inspiration to conform our own preferences to the divine will, whereby we are moved to the noblest kind of actions. Again, Christ is acknowledged to be the King of human hearts, on account of his love which passeth human understanding, and of his mercy and kindness, whereby he draweth all men unto him. For never hath anyone been loved so much at any time as Jesus Christ is loved, and that by so many different races. Neither will it happen in time to come that anyone shall be so loved. But although all this is true, Christ is also King in the proper and strict sense of the word. For if we ponder this matter more deeply we cannot but see that this title, as well as true kingly power, is rightly claimed for Christ as Man. As the Word of God he is of the same substance as the Father, and hath all things in common with the Father, and therefore in his divine nature he hath the highest and most absolute dominion over all created things. Hence it is only as Man that he can be said to have received from the Father the kingdom and the power and the glory.
As to the source of our Lord's kingly dignity, it is fittingly indicated by Cyril of Alexandria who saith : He doth possess dominion, if I may use the word, over all creatures ; a dominion not seized by violence, nor usurped from anyone, but possessed by virtue of his very being and nature. In him there is a marvellous union of the divine and human natures which is known as the hypostatic union, and this very union is a glorious manifestation of his dominion. That is to say, as a consequence of this hypostatic union, Angels and men do not only adore Christ as God, but are subject to his dominion as Man, and do obey him as such. For by reason of this hypostatic union, if for no other reason, Christ hath power over all created beings. And now, to explain the import and nature of this headship of his, let us say briefly that it consisteth in a three-fold power, namely, that of Law-giver, Judge, and Ruler. For if this power were lacking, we could scarcely discern wherein he hath any such headship. And, moreover the witness to our Redeemer's universal dominion, which same is not only implied but announced by Holy Scripture, is more than clear, so that it is an article of the Catholic Faith, proceeding from the truth that Christ Jesus was given to mankind as the Saviour of all those who put their faith in him. But this being so, it is clear that he is also to be the Law-giver for those who obey him. Thus, the Gospels not only relate that he made laws, but they also shew him in the act of promulgating them. In several different passages the divine Master is described as announcing in various ways that whosoever keepeth his commandments, doth thereby shew love for him, and the desire to persevere in loving him. As to his júdiciary power, Jesus himself hath told us that the Father hath conferred this upon him ; for at the time when the Jews accused him of having broken the law of Sabbath-rest by his miraculous cure of a sick man, he said : The Father judgeth no man, but hath committed all judgment unto the Son. Thus he hath authority to confer rewards or punishment upon the living, for authority so to do cannot be separated from his authority as Judge. From all this, his executive power (that is, his right to govern) is made clear, since all men must needs obey his rule, and those who disobey are subject to penalties from which there is no escape.
But, nevertheless, a kingdom such as this hath a special character, namely, that it is a spiritual kingdom, for it hath spiritual ends and purposes. The words quoted above from the Bible clearly indicate this, and the Lord Christ hath confirmed the same by his actions. On more than one occasion when the Jews―yea, when even the Apostles themselves―falsely imagined that the Messiah would presently free his people from Roman domination, and restore the Kingdom of Israel, he both dispelled and destroyed that fond hope. For he disclaimed the title of King when it was pressed upon him by the admiring multitude which thronged him ; he refused both the name and the honour by fleeing from them and concealing himself ; and he declared in the presence of the Roman Governour : My kingdom is not of this world. According to the Gospels it is a kingdom whose citizenship is prepared for by repentance, and bestowed by Baptism through faith. Although the latter is an outward rite, it doth both signify and produce an inward regeneration. Furthermore, this kingdom hath been raised up in direct opposition to the kingdom of Satan and the powers of darkness. Citizenship therein demandeth detachment from riches and worldly affairs, discipline of character, and hunger and thirst after righteousness ; and even more than this, that every citizen thereof is to deny himself, and take up his Cross. But since Christ as Redeemer hath purchased the Church with his own blood, and as Priest hath offered himself as a sacrifice for sin, which offering abideth forever, is it not evident that as King he is both our Redeemer and Priest? On the other hand, it is a wicked error to deny to Christ as Man the authority over civil affairs, since he hath from the Father such complete jurisdiction over created things that he could say : All power is given unto me in heaven and earth. Therefore, by our apostolic authority, we appoint the feast of Our Lord Jesus Christ the King, which same is to be observed annually throughout the entire world, on the last Lord's day in the month of October, that is to say, on the Sunday next before All Saints Day ; and likewise we enjoin, that the dedication of the human race to the Most Sacred Heart of Jesus be annually renewed upon that selfsame day.
A Homily by St. Augustine the Bishop
Here was a notable thing, the King of eternity had become the King of mortal men! In what way is it notable? In that Christ did not become the King of Israel to exact tribute, or to arm a body of men, or to conquer visible foes ; but rather that he might rule souls, and counsel them regarding eternity ; and that he might lead to the kingdom of heaven all such as believe in him, hope in him, and love him. In one such as he, it was condescension that he should desire to become the King of Israel. For he was the Son of God, co-equal with the Father, the Word by whom all things were made. To become such a King did not increase his power, but only betokened his mercy. For he who on earth was called the King of the Jews, in heaven was adored as Lord of the Angels. But is Christ King of the Jews only, or of the Gentiles also? Yea, of the Gentiles also. For when it was said of him in the prophetic Psalm : I have set my King upon my holy hill of Sion : lest anyone should say, on account of this word Sion, that he was appointed King of the Jews only, there is straightway added : Desire of me, and I shall give thee the heathen for thine inheritance, and the utmost parts of the earth for thy possession.
Jesus answered : My kingdom is not of this world ; if my kingdom were of this world, then would my servants fight, that I should not be delivered to the Jews ; but now is my kingdom not from hence. This is what the good Master would have us know. But first he had to shew how vain were the notions, current among men, regarding his kingship. It matters not whence Pilate heard them, whether from Jews or Gentiles. There was the notion that Christ ought to be punished on the grounds that he was a conspirator seeking unlawfully to set himself up as a king. Or the notion that reigning monarchs are wise to be jealous of any who aspire to the throne. Such notions assumed that Christ's kingdom would be set up against the Jews or the Romans. The first question of the Governour was : Art thou the King of the Jews? To which the Lord could have answered : My Kingdom is not of this world. But instead he answered with another question : Sayest thou this thing of thyself, or did others tell it thee of me? For he wished to shew from Pilate's answer that the Jews had laid a criminal charge against him on these grounds. In this wise did he lay open to us the thoughts of men, that they are but vain. And after Pilate's reply, he made answer, both to the Jews and the Gentiles, and that fittingly and opportunely : My Kingdom is not of this world.