The disciples just failed to cast out a demon, and when they questioned Jesus as to why, this was the answer they received. These may be some of the most abused, misunderstood, mis-applied verses in all of scripture. It is usually interpreted to be saying that there is some essential lack in the disciples (and us) that they could overcome if they just worked a bit harder at it. That they could grow more faith by doing this thing... context often intimates prayer and fasting. That these actions will make you stronger by default. Like lifting weights builds muscle; like eating ice cream builds fat. But consider this, that both of those activities prayer, and fasting are designed to make us LESS. Prayer brings us to the throne room of heaven, and while all of the resources we could ever want or need are available to us from our Father's storehouse, no one who has ever been aware of the awesome majesty of God can feel that they, are more... we feel our smallness, our weakness, we feel our NEED. And knowing that need, we seek our Father for our supply. Prayer makes us know that we are dependent. Fasting also weakens us, it puts down the flesh and properly done, enhances our sense of utter dependence upon God. Jesus said this, "if you have" but then followed it up by telling them plainly that all they have is NOT enough. My dear precious child of God, they, and we, need to know in the fiber of our souls that apart from constant and utter helpless dependence upon, and expectation of, help from God, we are hopeless. But, when we learn to lean in, to cast ourselves upon the faithfulness of our God and Father, then nothing is to much to expect from His omnipotent hand!!