There are only two sources for this kind of power.
17 He knew their thoughts, so he said, “Any kingdom divided by civil war is doomed. A family splintered by feuding will fall apart. 18 You say I am empowered by Satan. But if Satan is divided and fighting against himself, how can his kingdom survive?"
John 8:12 “I am the light of the world. If you follow me, you won’t have to walk in darkness, because you will have the light that leads to life.”
The reaction to Jesus' miracles were unbelievable sometimes, I remember the time that he healed the blind man and the Pharisees harass the man that was healed, this time a mute demon-possessed man is healed and again there isn't any joy. A miracle has just occurred and instead of a celebration there is a theological debate, the man just fades into the background as the crowd decides whether or not Jesus is working for the devil.
They knew that the power to do the things Jesus was doing could only come from God or Satan, the Pharisees cannot acknowledge that his power is from God so they have a problem, that leaves only one option and so they decide to say the power is from Satan.
The problem with saying that Jesus power is coming from Satan is that he and Jesus have never worked together to accomplish anything. How could the light of the world be working with power from the prince of darkness? Why would Satan go against one of his own? If it were not true then why would many of the demons fear Jesus and acknowledge him as the Son of God when they met him?
There was another group of people in the crowd besides the group that debated about the source of Jesus power, this group wanted Jesus to do some more miracles to test Jesus. Didn't they see enough evidence already?
It may be more clear to us looking back at history than it was to the people that were around Jesus during his ministry, there is a lot of benefit in seeing the bigger picture. We don't know how we would of reacted to Jesus ministry and whether or not we would have acknowledged that his power is from God.
I need to be careful to acknowledge his power all around me everyday.
You are an awesome, powerful God! It is wonderful to know that you are in control and that Satan has been defeated.