For truly, I say to you, if you have faith like a grain of mustard seed,
you will say to this mountain, 'Move from here to there,' and it will move,
and nothing will be impossible for you.
When the crowd had dispersed, the disciples came to Jesus and asked why they were unable to heal the boy. They had, after all, done so in the past in their travels when Jesus had commissioned them two by two, and they clearly were wondering what they were missing. Jesus gave them an answer which made them (and us) ponder, "Because of your little faith." Jesus really applies the hammer by stating, "if you had faith like a grain of mustard seed ..." Well, I must not have such a faith, because I have not told any mountains to move or trees to jump in the river.
If I don't have such faith, how can I be saved? The answer is in the realization that faith is not really ours. It does not come from us. Faith is a gift from God by the power of the Holy Spirit. It is precisely when we come to believe that "I have to believe" by my own thinking, reasoning, feeling, or experience, that we are in most danger of not having faith.
This little narrative following the transfiguration is a reminder to the disciples and to us to never take our minds off of Jesus, the One who died for us, is saving us, and will finally raise us from the dead. It was his faith in his Father's will which won the victory for us over sin, death, and the devil. It is no effort of ours. If and when we actually do have a victory over a demon that haunts us, a sickness that tries us, a temptation that has vexed us, or any other blessing or joy in our lives, we ought/should/must give thanks and praise to God for such things.
Faith is not ours to be taken for granted, but a gift of God to be appreciated and valued every moment of every day. Our prayers for success or blessing in any circumstance of life need to be accompanied by "Thy will be done." Jesus did not get the answer from the Father that he was praying for in the Garden of Gethsemane to "let this cup pass from me." The apostle Paul prayed three times that his "thorn in the flesh" be removed, only to receive the answer, "My grace is sufficient for you." (2 Corinthians 12:7-9). The Father knows the course He has laid out for us, and sometimes it includes reminders of just how much we depend on Him for all things. Even our faith in Him is not our own. But His faith accomplishes all things that He has purposed. This is the faith that He has given us.
Remember Whose you are,