It has long been a common custom to give to Christ the metaphorical title of “King,” because of the high degree of perfection whereby he excels all creatures.
But if we ponder this matter more deeply, we cannot but see that the title and the power of King belongs to Christ as man in the strict and proper sense too. For it is only as man that he may be said to have received from the Father “power and glory and a kingdom,” since the Word of God, as consubstantial with the Father, has all things in common with him, and therefore has necessarily supreme and absolute dominion over all things created.
Do we not read throughout the Scriptures that Christ is the King?
If We ordain that the whole Catholic world shall revere Christ as King, We shall minister to the need of the present day, and at the same time provide an excellent remedy for the plague which now infects society.
-Pius XI Quas Primas