Matthew 12:22-28 (ESV):
22 Then a demon-oppressed man who was blind and mute was brought to him, and he healed him, so that the man spoke and saw. 23 And all the people were amazed, and said, “Can this be the Son of David?” 24 But when the Pharisees heard it, they said, “It is only by Beelzebul, the prince of demons, that this man casts out demons.” 25 Knowing their thoughts, he said to them, “Every kingdom divided against itself is laid waste, and no city or house divided against itself will stand. 26 And if Satan casts out Satan, he is divided against himself. How then will his kingdom stand? 27 And if I cast out demons by Beelzebul, by whom do your sons cast them out? Therefore they will be your judges. 28 But if it is by the Spirit of God that I cast out demons, then the kingdom of God has come upon you.
Verse 26 reveals the existence of the Kingdom of Satan. What is the Kingdom of Satan?