14When they came to the crowd, a man came to him, knelt before him,15and said, “Lord, have mercy on my son, for he is an epileptic and he suffers terribly; he often falls into the fire and often into the water. 16And I brought him to your disciples, but they could not cure him.” 17Jesus answered, “You faithless and perverse generation, how much longer must I be with you? How much longer must I put up with you? Bring him here to me.” 18And Jesus rebuked the demon, and it came out of him, and the boy was cured instantly. 19Then the disciples came to Jesus privately and said, “Why could we not cast it out?” 20He said to them, “Because of your little faith. For truly I tell you, if you have faith the size of 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.” (Matthew 17:14-21, NRSV)
I think we hear this as Jesus scolding the disciples, but I like to think it is more that Jesus is telling them maybe they expect too much. If you had the faith the size of a mustard seed you could move a mountain. But who really needs to move a mountain? But the faith you have is enough. You see Jesus is still able to do everything and do things through us, so all we need is the faith we have.
Sometimes we think we need to do the big things when Jesus is asking us to just follow and believe and the faith we have is enough for us.
So how much faith do you need?