And if Satan cast out Satan, he is divided against himself; how shall then his kingdom stand?
All Commentaries on Matthew 12:26 Go To Matthew 12
Augustine of Hippo
In saying this, he wanted it to be understood from their confession that they had chosen to live in him by not believing in the kingdom of the devil and that the devil could not stand divided against himself. So let the Pharisees choose what they want. If Satan could not cast out Satan, they could find nothing to say against the Lord. But if Satan can cast out Satan, let them look out for themselves all the more and let them abandon his kingdom because it cannot stand divided against itself.