Fasting delivers no one.
19 Then the disciples came to Jesus and asked privately, Why could we not drive it out?
20 He said to them, Because of the littleness of your faith [that is, your lack of firmly relying trust]. For truly I say to you, if you have faith [that is living] like a grain of mustard seed, you can say to this mountain, Move from here to yonder place, and it will move; and nothing will be impossible to you.
So if fasting drives out the demon Jesus did not know what He was saying in v20.
19 Then the disciples came to Jesus and asked privately, Why could we not drive it out?
20 He said to them, Because of the littleness of your faith [that is, your lack of firmly relying trust]. For truly I say to you, if you have faith [that is living] like a grain of mustard seed, you can say to this mountain, Move from here to yonder place, and it will move; and nothing will be impossible to you.
So if fasting drives out the demon Jesus did not know what He was saying in v20.