v 34. But the Pharisees said, “He can cast out demons because he is empowered by the prince of demons.”
To say that Jesus was under the sway of demonic forces was an attempt to discredit Him, and put Him on the opposite side from sincere Jews. The battle lines for later conflict were being set up. ‘We, good orthodox Jews, are on the right side,’ opined the Pharisees, thus branding Jesus as a demonic usurper, and so blackening His character.
Notice the conflict bubbling under the surface when the Pharisees criticised Jesus, saying ‘Why does your teacher eat with such scum? ‘ (v 11)