Then the disciples came to Jesus privately and said, “Why could we not cast it out?” So Jesus said to them, “Because of your unbelief; for assuredly, I say to you, if you have faith as a mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move, and nothing will be impossible for you. However, this kind does not go out except by prayer and fasting.”
(Matthew 17:19-21 NKJV)
A man came to the disciples of Christ for a miracle. His son was demonized, but upon praying for the child the disciples could not cast out the evil spirit. Why were they unable? Was it due to their lack of power? Did they not have the ability? They absolutely did! Jesus had already given them authority over all the power of the enemy. The answer lies in the text above. Why could they not cast it out? Because of their unbelief. This is the only explanation in the Bible given for unanswered prayer. Jesus said, “nothing will be impossible for you.” In another text, he said, “all things are possible for the one who believes.” There are two places where miracles were hindered from happening in the gospels. In this text above, and when Jesus visited his own hometown. In both places, the miracles were quenched due to unbelief. We must stop blaming God's sovereign will for our lack of possessing the promises of God. If we are not possessing what God has promised, it is due to unbelief. In the text above Jesus not only shows us the problem, but he also gives us the cure. What did the disciples need to do in order to conquer unbelief and cast that kind of demon out? Pray and fast! Fasting and prayer are the cure for unbelief. How do prayer and fasting destroy unbelief? Fasting is an act of faith. Your fasting proves and refines your faith. Would you starve for a God you don't believe in? No, day number two of your stomach rumbling and you would be in the Mcdonald's drive-thru. Your flesh begins to scream, “feed me, this isn't working, you're not getting anything out of doing this,” but when you push past that urge and press deeper into God, you take that little part of unbelief that your flesh holds on to and you nail it to the cross. You wouldn't starve for a God you don't believe in, and you wouldn't spend hours talking to a God who is not real. When you fast and pray repeatedly, you crucify whatever doubt and unbelief that remains in you.