Mateo 12:25-26

Probably Jesus’ knew His critics’ thoughts as anyone else who had suffered such an attack would (cf. Matthew 9:4). Alternatively this may be a statement of Jesus’ omniscience. Any kingdom, city, or household that experiences internal conflict will destroy itself eventually if the strife continues. This holds true for the domain over which Satan rules as well. For Satan to cast out demons would amount to his casting out himself since the demons do his work.