What Does Jesus Mean by ‘Faith as Small as a Mustard Seed?’

...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... – Matthew 17:20

Have you ever wished that you had more faith? Stronger faith? Deeper faith? Sometimes, we think that if we can only muster up more faith from within ourselves, we can accomplish more.

One of the greatest mistakes we can make in the Christian life is to think that power is sourced in faith itself. But on two separate occasions in the Gospel Accounts, Jesus talks about a “mustard seed” faith that can result in great things.

What Does ‘Faith as Small as a Mustard Seed’ Even Mean?

Why does Jesus use a mustard seed to describe faith? In Jesus’ day, the mustard seed was used proverbially to represent the smallest of things. And with a diameter of 1 to 2 millimetres, it’s a fitting illustration!

By using this illustration to describe faith, Jesus is directing our attention, not to the quantity or strength of our faith, but to the object of our faith. Our faith is only as strong as the object in which its placed.

If our faith, even if it’s the size of a mustard seed, is placed in the all-powerful God, great things can happen. In The Gospel According to Matthew, Leon Morris says, “It is not necessary to have great faith; even a small faith is enough, as long as it is faith in the great God.”

The Bible defines faith as a self-emptied, dependent assurance in God’s character and promises. The most famous biblical definition of faith is Hebrews 11:1: “Now faith is the assurance of things hoped for, the conviction of things not seen.”

self-effort (Ephesians 2:8-9) and has no reliance on human strength and wisdom (1 Cor. 2:5). In other words, when we talk about biblical faith, all the strength and power come from the object of faith (God himself), not the “size” of faith—even a “mustard seed” faith will do.

What Bible Verses Mention Mustard Seed Faith?

 Jesus uses this analogy twice—once in Matthew 17:20 and once in Luke 17:6. In each of these accounts, Jesus is confronting a lack of faith in the disciples.

In Matthew 17, a man pleads with Jesus to heal his son who was suffering from an oppressive demon. The man tells Jesus that he had already gone to his disciples, but “they could not heal him” (Matthew 17:16).

Jesus responds to this with sorrow over the “faithless and twisted generation” and then casts the demon out of the boy. When the disciples ask Jesus why they couldn’t cast him out, Jesus responds, “Because of your little faith. For truly, I say to you, if you have faith like a grain 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.”

In Luke 17, Jesus is teaching his disciples about forgiveness, telling them that, even if someone offends you “seven times in the day,” they were to forgive him seven times (Luke 17:3-4). Upon hearing this difficult command, the disciples respond, “Increase our faith!” (Luke 17:5).

Jesus once again uses the illustration of the mustard seed: “If you had faith like a grain of mustard seed, you could say to this mulberry tree, ‘Be uprooted and planted in the sea,’ and it would obey you” (Luke 17:6).

The disciples had a misplaced faith. They couldn’t cast out the demon because, according to Leon Morris’ commentary, “perhaps the disciples had been treating their power to cast out devils as a new possession of their own—a kind of magic—they would go through their routine and the devil would come out.”

They assumed that “more faith” would give them the power to forgive. But on both occasions, Jesus tells them that if they have faith (even if it’s the size of a 1-millimeter seed) that is placed in the all-powerful God—big things happen.

In Matthew: an Introduction and Commentary, R.T. France writes, “It is important to observe here that it is not the ‘amount’ of faith which brings the impossible within reach, but the power of God, which is available to even the ‘smallest’ faith.”

Can It Move Mountains?

Was Jesus being literal when he said that faith could uproot a mountain and cast it into the sea? No. If it were literal, I would be on my way to the Rocky Mountains to give it a shot.

Just as the “mustard seed” was a proverbial illustration, so was the mountain.

According to R.T. France in Matthew: an Introduction and Commentary, mountains being uprooted and moved was a common illustration to describe “the most improbable occurrence: (Isaiah 54:10; 1 Cor 13:2). The stark contrast between the smallest of seeds and the immensity of a mountain range is a powerful one.

Jesus is telling us that only faith in a powerful God can accomplish the things that only a powerful God can do. This does not mean, however, that we can harness God’s power to accomplish whatever we desire. We cannot hijack the power of God for our own purposes.

If faith is a self-emptied, dependent assurance in the character and promise of God, then that faith will only pursue things that align with his character and agree with his promises. True faith is aligned with his will as revealed in Scripture—it’s not a magical charm to pursue our own dreams.

Dear God, You are the God of the impossible. I am so weak and frail, but you are all-powerful. Thank you that my hope doesn’t rest in the strength of my own faith, but in your strength. However small it is, keep my faith focused on you alone. Convince and comfort me with your character and promises. Help me align my will with yours. Keep me in your Word so that my faith is rooted in a firm foundation. In Jesus’ name, Amen.