Demons are spirits.
They can occupy people and animals.
They can speak.
So the
demons begged Him, saying, “If You cast us out, permit us to go away into the herd of swine.”
Matthew 8:31
Demons oppress people and can cause them to be deaf and mute.
As they went out, behold, they brought to Him a man,
mute and demon-possessed. And
when the demon was cast out, the mute spoke. And the multitudes marveled, saying, “It was never seen like this in Israel!” Matthew 9:32
Again, demons are spirits and can speak.
Then He healed many who were sick with various diseases, and cast out many demons; and
He did not allow the demons to speak, because they knew Him.
Mark 1:34
Believers do the works of Jesus Christ as well.
And these signs will follow those who believe: In My name they will cast out demons; they will speak with new tongues;
Mark 16:17
Jesus cast out demons wherever He went, and destroyed the works of the devil.
JLB