3 But lest the exceeding greatness of His praises should produce a sort of extravagant feeling, the Jews honoring John above Christ; mark how He corrects this also. For as the things which edified His own disciples did harm to the multitudes, they supposing Him an easy kind of person; so again the remedies employed for the multitudes might have proved more mischievous, they deriving from Christ's words a more reverential opinion of John than of Himself.
Wherefore this also, in an unsuspected way, He corrects by saying, “He that is less, in the kingdom of Heaven is greater than he.” Less in age, and according to the opinion of the multitude, since they even called Him “a gluttonous man and a winebibber;” and, “Is not this the carpenter's son?” and on every occasion they used to make light of Him.
“What then?” it may be said, “is it by comparison that He is greater than John?” Far from it. For neither when John says, “He is mightier than I,” does he say it as comparing them; nor Paul, when remembering Moses he writes, “For this man was counted worthy of more glory than Moses,” does he so write by way of comparison; and He Himself too, in saying, “Behold, a greater than Solomon is here,” speaks not as making a comparison.
Or if we should even grant that this was said by Him in the way of comparison, this was done in condescension, because of the weakness of the hearers. For the men really had their gaze very much fixed upon John; and then he was rendered the more illustrious both by his imprisonment, and by his plainness of speech to the king; and it was a great point for the present, that even so much should be received among the multitude. And so too, the Old Testament uses in the same way to correct the souls of the erring, by putting together in a way of comparison things that cannot be compared; as when it says, “Among the gods there is none like You, O Lord:” and again, “There is no god like our God.”
Now some affirm, that Christ said this of the apostles, others again, of angels. Thus, when any have turned aside from the truth, they are wont to wander many ways. For what sort of connection has it, to speak either of angels or of apostles? And besides, if He were speaking of the apostles, what hindered his bringing them forward by name? Whereas, when He is speaking of Himself, He naturally conceals His person, because of the still prevailing suspicion, and that He may not seem to say anything great of Himself; yea, and we often find Him doing so.
But what is, “In the kingdom of heaven?” Among spiritual beings, and all them that are in heaven.
And moreover His saying, “There has not risen among them that are born of women a greater than John,” suited one contrasting John with Himself, and thus tacitly excepting Himself. For though He too were born of a woman, yet not as John, for He was not a mere man, neither was He born in like manner as a man, but by a strange and wondrous kind of birth.
Source: Homilies on the Gospel of St. Matthew (New Advent)