11 Moreover, Christ himself speaks of his own kingly authority: in his last discourse, speaking of the rewards and punishments that will be the eternal lot of the just and the damned; in his reply to the Roman magistrate, who asked him publicly whether he were a king or not; after his resurrection, when giving to his Apostles the mission of teaching and baptizing all nations, he took the opportunity to call himself king, confirming the title publicly, and solemnly proclaimed that all power was given him in heaven and on earth. These words can only be taken to indicate the greatness of his power, the infinite extent of his kingdom. What wonder, then, that he whom St. John calls the "prince of the kings of the earth" appears in the Apostle's vision of the future as he who "hath on his garment and on his thigh written 'King of kings and Lord of lords!'." It is Christ whom the Father "hath appointed heir of all things"; "for he must reign until at the end of the world he hath put all his enemies under the feet of God and the Father."
Source: Quas Primas (Vatican.va)