The little mustard seed is used in both Matthew and Luke to provide a picture of faith. (It's also found in Matthew, Mark and Luke where Jesus described the kingdom of heaven.) In Matthew chapter 17, Jesus was talking to his disciples about why they could not cast out a demon to heal a boy of his seizures; whereas in Luke 17 He was dealing with the human difficulty of forgiving people.
When they came to the crowd, a man approached Jesus and knelt before him. "Lord, have mercy on my son," he said. "He has seizures and is suffering greatly. He often falls into the fire or into the water. I brought him to your disciples, but they could not heal him."
"O unbelieving and perverse generation," Jesus replied, "how long shall I stay with you? How long shall I put up with you? Bring the boy here to me." Jesus rebuked the demon, and it came out of the boy, and he was healed from that moment.
Then the disciples came to Jesus in private and asked, "Why couldn't we drive it out?"
He replied, "Because you have so little faith. I tell you the truth, if you have faith as small as a mustard seed, you can say to this mountain, 'Move from here to there' and it will move. Nothing will be impossible for you."
In this passage, the emphasis is not on healing but on the ability to "move this mountain" –the mountain being something that is overwhelming, daunting, seemingly impossible. The mountain represents those things that only God can overcome. The mustard seed –although tiny– is real and tangible. The point of the comparison is that faith must be more than a concept in your mind. It must produce results in your life –something real that you attribute to God's compassion for you.
No doubt you have heard the old example about having faith in a chair. Saying you trust the chair to support you is nothing more than words until that faith is exercised. It's when you actually sit and rest in it that faith is realized. That is how faith is proved out. It's only after experiencing the sitting –and the resting– that you can know that the chair is trustworthy.
As you journey through life, you can see faith do the same things that seeds do. They grow into something much bigger than what they started. Your faith –trust in God– will also grow and you will be amazed by what He does with you. Does that mean that if you trust God to change something (take away the bad and bring on the good circumstances), that it will happen? No, moving the mountain is about taking away the fearful thoughts so that the circumstances are no longer something to dread. Circumstances will no longer control your life because you will trust God to do what is good for you –and for those around you.
Jesus said to his disciples: "Things that cause people to sin are bound to come, but woe to that person through whom they come. It would be better for him to be thrown into the sea with a millstone tied around his neck than for him to cause one of these little ones to sin. So watch yourselves. "If your brother sins, rebuke him, and if he repents, forgive him. If he sins against you seven times in a day, and seven times comes back to you and says, 'I repent,' forgive him."
The apostles said to the Lord, "Increase our faith!"
He replied, "If you have faith as small as a mustard seed, you can say to this mulberry tree, 'Be uprooted and planted in the sea,' and it will obey you.
"Suppose one of you had a servant plowing or looking after the sheep. Would he say to the servant when he comes in from the field, 'Come along now and sit down to eat'? Would he not rather say, 'Prepare my supper, get yourself ready and wait on me while I eat and drink; after that you may eat and drink'? Would he thank the servant because he did what he was told to do? So you also, when you have done everything you were told to do, should say, 'We are unworthy servants; we have only done our duty.'" Now on his way to Jerusalem, Jesus traveled along the border between Samaria and Galilee.
As he was going into a village, ten men who had leprosy met him. They stood at a distance and called out in a loud voice, "Jesus, Master, have pity on us!" When he saw them, he said, "Go, show yourselves to the priests." And as they went, they were cleansed. One of them, when he saw he was healed, came back, praising God in a loud voice. He threw himself at Jesus' feet and thanked him –and he was a Samaritan. Jesus asked, "Were not all ten cleansed? Where are the other nine? Was no one found to return and give praise to God except this foreigner?" Then he said to him, "Rise and go; your faith has made you well."
This passage began with a discourse on forgiveness where the disciples asked Him for more faith so that they too could forgive. Throughout the Bible the amount of power, or the position in society, that people held is represented by trees. As an example, there is a tree described in Daniel (it is Nebuchadnezzar's position of being king) that towers over all of the plants and animals in the field. And it provides shelter and food for those it is over. Now in this passage from Luke, the mulberry tree is likened to a person who has "lorded over" you and caused you great trouble.
Being able to forgive that person requires faith –faith that God is using that trouble to transform you into the likeness of His Son –faith that God is concerned with you and your future –faith that He will carry you through your current situation and bring you into maturity. Just like the mustard seed that starts tiny and becomes a great tree –you will become a person of influence for others. And as a tree you will produce fruit –fruit of the Spirit.
Jesus let them think about this for a while. Then on their walk to their next lesson, He drove the point home by relating His personal experiences. After He healed ten lepers, only one of them gave thanks. Does He hold their unforgiving attitudes against them? Of course not. Through this story, He lets us see His heart so that we can understand how we humans offend Him and yet He continues to love and accept us. In one way or another, we are all like the nine lepers that didn't give thanks. Jesus trusted His Father to work out all things for good. Likewise, we too can see the results of our faith when we turn our weaknesses over to God –wanting with all our hearts to forgive without ever again remembering the offense. Feeling the release from anger toward the offending person is like seeing your mustard seed begin to grow.
God took the Israelites through many journeys. Whenever there were difficult encounters, they saw Him at work. He took them across the sea and the river; He gave them food and drink; He drove out their enemies before them. They piled up stones as reminders of what He had done for them at these junctions. Remembering His faithfulness is like looking at the mustard seed to remind yourself that He is real –that He gives life its purpose. Our heavenly Father provided our Sacrifice for all times –His Son– as redemption for us all! That's why we are reminded to give thanks in all situations and to praise Him for all that He is and does.