John Chrysostom — as excerpted in the Catena Aurea on Matthew 12:25-26

“(Hom. xli.) Above they had accused Christ of having cast out dæmons by Beelzebub; but then He did not reprove them, suffering them, if they would, to acknowledge Him from further miracles, and to learn His greatness from His doctrine. But because they continued to maintain the same things, He now rebukes them, although their accusation had been very unreasonable. But jealousy recks not what it says, so that only it say somewhat. Yet does not Christ contemn them, but answers with a gracious mildness, teaching us to be gentle to our enemies, and not to be troubled, even though they should speak such things against us, as we neither acknowledge in us, nor have any reasonableness in themselves. Therein also He proves that the things which they had said against Him were false, for it is not of one having a dæmon to shew such mercy, and to know the thoughts. Moreover, because this their accusation was very unreasonable, and they feared the multitude, they did not dare to proclaim it openly, but kept it in their thoughts; wherefore he says, Knowing their thoughts. He does not repeat their thoughts in His answer, not to divulge their wickedness; but He brings forward an answer; it was His object to do good to the sinners, not to proclaim their sin. He does not answer them out of the Scriptures, because they would not hearken to Him as they explained them differently, but He refutes them from common opinions. For assaults from without are not so destructive as quarrels within; and this is so in bodies and in all other things. But in the mean while He draws instances from matters more known, saying, Every kingdom divided against itself shall be brought to desolation; for there is nothing on earth more powerful than a kingdom, and yet that is destroyed by contention. What then must we say concerning a city or a family, that whether it be great or small, it is destroyed when it is at discord within itself.”