6 Then, because what He had said was mere affirmation, He confirms it by the miracle; as indeed He shows the miracles in their turn, by the subsequent accomplishment of the prediction. He accordingly, who disbelieves the health which the servant then received, let him from the prophecy, which has this day come to pass, believe that other also. For so that prophecy again, even before the event, was made manifest to all by the sign which then took place. To this end, you see, having first uttered that prediction, then and not before He raised up the sick of the palsy; that He might make the future credible by the present, and the less by the greater. Since for virtuous men to enjoy His good things, and for the contrary sort to undergo His penalties, were nothing improbable, but a reasonable event, and according to the tenor of laws: but to brace up the feeble, and to raise the dead, was something beyond nature.
But nevertheless, unto this great and marvellous work the centurion too contributed no little; which thing, we see, Christ also declared, saying, “Go your way, and as you have believed, so be it done unto you.” Do you see how the health of the servant proclaimed aloud both Christ's power, and the faith of the centurion, and also became a pledge of the future? Or rather it was all a proclamation of Christ's power. For not only did He quite heal the servant's body, but the soul also of the centurion He did Himself bring over unto the faith by His miracles.
And do thou look not to this only, that the one believed, and the other was healed, but marvel how quickly also. For this too the evangelist declared, saying, “And his servant was healed in the self-same hour:” even as of the leper also he said, “he was straightway cleansed.” For not by healing, but by doing so both in a wonderful manner and in a moment of time, did He display His power. Neither in this way only does He profit us, but also by his constant practice, in the manifestation of His miracles, of opening incidentally His discourses about His kingdom, and of drawing all men towards it. For, those even whom He was threatening to cast out, He threatened not in order to cast them out, but in order that through such fear, He might draw them into it by His words. And if not even hereby were they profited, theirs is the whole blame, as also of all who are in the like distemper.
For not at all among Jews only may one see this taking place, but also among them that have believed. For Judas too was a child of the kingdom, and it was said to him with the disciples, “You shall sit on twelve thrones;” yet he became a child of hell; whereas the Ethiopian, barbarian as he was, and of them “from the east and west,” shall enjoy the crowns with Abraham, and Isaac, and Jacob. This takes place among us also now. “For many,” says He, “that are first shall be last, and the last first.” And this He says, that neither the one may grow languid, as unable to return; nor the others be confident, as standing fast. This John also declared before from the beginning, when he said, “God is able of these stones to raise up children unto Abraham.” Thus, since it was so to come to pass, it is proclaimed long before; that no one may be confounded at the strangeness of the event. But he indeed speaks of it as a possible thing (for he was first); Christ on the other hand as what will surely be, affording the proof of it from His works.
Source: Homilies on the Gospel of St. Matthew (New Advent)