Matthew 17:14-20The Lord commanded, "Love with all your hearts and minds. He further reminded them, "I gave you everything you did not plant." It is God who is all powerful.
The reason why our prayers are not answered is because we haven't loved the Lord enough. We are more interested in the gifts, not the giver. And when the Lord doesn't grant the things that we ask for, we doubt him.
In the gospel, Jesus reprimanded his disciples. "‘Faithless and perverse generation!’ Jesus said in reply ‘How much longer must I be with you? ... ‘Because you have little faith. I tell you solemnly, if your faith were the size of a mustard seed you could say to this mountain, “Move from here to there,” and it would move; nothing would be impossible for you.’"
What does it mean to have faith?
First, it means to rely totally on God. There a quote that says, "When you pray, treat as if everything depended on God." Total reliance is to give to God what is due Him - adoration and submission to his will, not ours.
Second, it means to have courage to do God's will. To continue the quote, "When you work, treat as if everything depended on yourself." Even though we realize that even our strength comes from God, we now use it to serve him, not questioning his authority, but submitting everything to his care, even our own lives.
Third, faith is nourished by hope and pruned to perfection in love. Let's hope against hope that God's will may triumph. This is the sign of true faith. Moreover, if a man has faith, he will not have second thoughts of giving himself for others because he has God's love inside him.