Luke 11:18

(ubi sup.) He did not answer them from the Scriptures, since they gave no heed to them, explaining them away falsely; but he answers them from things of every day occurrence. For a house and a city if it be divided is quickly scattered to nothing; and likewise a kingdom, than which nothing is stronger. For the harmony of the inhabitants maintains houses and kingdoms. If then, says He, I cast out devils by means of a devil, there is dissension among them, and their power perishes. Hence He adds, But if Satan be divided against himself, how shall he stand? For Satan resists not himself, nor hurts his soldiers, but rather strengthens his kingdom. It is then by Divine power alone that I crush Satan under my feet.

But if Satan is divided against himself, how will his kingdom stand, because you say that I cast out demons in Beelzebub? By saying this, he wanted it to be understood from their own confession that by not believing in him, they had chosen to be in the kingdom of the devil, which certainly could not stand divided against itself. Therefore, let the Pharisees choose what they wish. If Satan cannot cast out Satan, they could find nothing to say against the Lord. But if he can, let them be much more cautious and withdraw from his kingdom, which cannot stand divided against itself. By what means the Lord Christ casts out demons, let them consider what follows, so that they do not think him to be the prince of demons.

In like manner, it is He who will give the Holy Spirit, at whose command is also the unholy spirit. When He cast out the "demon which was dumb" (and by a cure of this sort verified Isaiah), and having been charged with casting out demons by Beelzebub, He said, "If I by Beelzebub cast out demons, by whom do your sons cast them out? " By such a question what does He otherwise mean, than that He ejects the spirits by the same power by which their sons also did-that is, by the power of the Creator? For if you suppose the meaning to be, "If I by Beelzebub, etc., by whom your sons? "-as if He would reproach them with having the power of Beelzebub,-you are met at once by the preceding sentence, that "Satan cannot be divided against himself." So that it was not by Beelzebub that even they were casting out demons, but (as we have said) by the power of the Creator; and that He might make this understood, He adds: "But if I with the finger of God cast out demons, is not the kingdom of God come near unto you? " For the magicians who stood before Pharaoh and resisted Moses called the power of the Creator"the finger of God.