“Then Jesus answered and said, O faithless and perverse generation, how long shall I be with you? how long shall I suffer you?...” - Matthew 17:17.
When Jesus Christ came to meet a multitude that had been waiting for him, a man brought him his son whom the devil had afflicted with madness, such that sometimes he falls into fire, at times into the water. That the young man could be so tormented without his being able to control himself gave no small anxiety to his parents in that his life was in continual danger. - Mark 9:21-23.
Jesus Christ rebuked his disciples stating that their inability to cure the boy was because of their unbelief. He then said “When Jesus saw that the people came running together, he rebuked the foul spirit, saying unto him, Thou dumb and deaf spirit, I charge thee, come out of him, and enter no more into him.” (Mark 9:25) The account of Matthew says “the child was cured from that very hour”. (Matthew 17: 18) Concerned that they could not cast out the demon the disciples later came to Christ and he told them that their problem was their unbelief. “And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you.” (Matthew 17:20) Scripture says “Cast thy burden upon the LORD, and he shall sustain thee: he shall never suffer the righteous to be moved.” - Psalm 55:22