(Matthew 12:24-28) But when the Pharisees heard it, they said, This fellow doth not cast out devils, but by Beelzebub the prince of the devils. And Jesus knew their thoughts, and said unto them, Every kingdom divided against itself is brought to desolation; and every city or house divided against itself shall not stand: And if Satan cast out Satan, he is divided against himself; how shall then his kingdom stand? And if I by Beelzebub cast out devils, by whom do your children cast them out? therefore they shall be your judges. But if I cast out devils by the Spirit of God, then the kingdom of God is come unto you.
Jesus seems to give this passage to prove that the kingdom of God comes through him, but the argument doesn't prove that at all.
Jesus mentions two ways of casting out demons, two powers that can cast out demons:
The Pharisees claim that Jesus casts out demons by the power of Satan. In response Jesus asks whether the Pharisees cast out demons also by the power of Satan. The problem is that Jesus equates the power of the Pharisees to cast out demons with his own power to cast out demons.
Jesus mentions two kingdoms:
Jesus argues that Satan would never cast out demons because of the principle that in doing so, his kingdom of darkness would collapse. Therefore, anyone who casts out demons must do so by the Spirit of God.
In claiming this, Jesus is in effect saying that the Pharisees are part of the kingdom of God because they cast out demons. But how can people by part of the kingdom of God who state that Jesus is casting out demons by the power of Satan?
In claiming that casting out demons is a sign of being part of the kingdom of God, Jesus does not allow for the possibility that Satan might allow those in Satan's kingdom to cast out demons if it suits his nefarious purpose.
The solution to these problems is in the idea that Satan's kingdom of darkness will not stand because those in his kingdom are divided against one another. Satan's kingdom of darkness is a kingdom of division, disunity, and discord. Thus, anyone who is not a member of the kingdom of God is in active opposition to the kingdom of God and they will seek to draw people away from the light of God. The Pharisees can perform works of Satan. An example of this is in accusing Jesus of being of Satan.