Dixit Pilatus ad Iesum: "Tu es rex Iudæorum?" Respondit Iesus: "A temetipso hoc dicis, an alii dixerunt tibi de me?" Respondit Pilatus: "Numquid ego Iudæus sum? Gens tua et pontifices tradiderunt te mihi: quid fecisti?" Respondit Iesus: "Regnum meum non est de hoc mundo. Si ex hoc mundo esset regnum meum, ministri mei utique decertarent ut non traderer Iudæis: nunc autem regnum meum non est hinc."
(From the Gospel for the Feast of Our Lord Jesus Christ the King, John xviii, 33-36: " Pilate said to Jesus: Art Thou the King of the Jews? Jesus answered: Sayest thou this thing of thyself, or have others told it thee of Me? Pilate answered: Am I a Jew? Thine own nation and the chief priests have delivered Thee up to me: what hast Thou done? Jesus answered: My kingdom is not of this world. If My kingdom were of this world, my servants would certainly strive that I should not be delivered to the Jews: by now my Kingdom is not from hence.")
Hear then, ye Jews and Gentiles! Hear, O circumcision! Hear, O uncircumcision! Hear, all ye kingdoms of the earth: I interfere not with your government in this world, "My kingdom is not of this world."
Cherish ye not the utterly vain terror that threw Herod the Elder into consternation when the birth of Christ was announced, and led him to the murder of so many infants in the hope of including Christ in the fatal number, made more cruel by his fear than by his anger: "My kingdom," He said, "is not of this world."
What would you more? Come to the kingdom that is not of this world! Come, believing, and fall not into the madness of anger through fear!
He says, indeed, prophetically, of God the Father, "Yet have I been appointed king by Him upon His holy hill of Zion;" but that hill of Zion is not of this world. For what is His kingdom, save those who believe in Him, to whom He says, "Ye are not of the world, even as I am not of the world"? And yet He wished them to be in the world: on that very account saying of them to the Father, "I pray not that Thou shouldest take them out of the world, but that Thou shouldest keep them from the evil." Hence also He says not here, "My kingdom is not" in this world; but, "is not of this world." And when He proved this by saying, "If my kingdom were of this world, then would my servants fight, that I should not be delivered to the Jews," He saith not, "But now is my kingdom not" here, but, "is not from hence."
For His kingdom is here until the end of the world [hic est enim regnum eius usque in finem sæculi...], having tares intermingled therewith until the harvest; for the harvest is the end of the world, when the reapers, that is to say, the angels, shall come and gather out of His kingdom everything that offendeth; which certainly would not be done, were it not that His kingdom is here! [...quod utique non fieret, si regnum eius non esset hic.]
But still it is not from hence; for it only sojourns as a stranger in the world: because He says to His kingdom, "Ye are not of the world, but I have chosen you out of the world." They were therefore of the world, so long as they were not His kingdom, but belonged to the prince of this world.
Of the world therefore are all mankind, created indeed by the true God, but generated from Adam as a vitiated and condemned stock; and there are made into a kingdom no longer of the world, all from thence that have been regenerated in Christ. For so did God rescue us from the power of darkness, and translate us into the kingdom of the Son of His love: and of this kingdom it is that He saith, "My kingdom is not of this world;" or, "My kingdom is not from hence."
In Evangelium Ioannis - Tractatus CXV
(Our traditional post for Christ the King)