Ever wondered why Jesus compared faith to something as tiny as a mustard seed? In Matthew 17:20, Jesus tells His disciples, “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.” But what was Jesus really teaching about faith?

 

THE CONTEXT BEHIND THE METAPHOR

To understand this striking statement, we need to look at its context. In Matthew’s account, the disciples had just failed to cast out a demon. Confused and discouraged, they asked Jesus privately why they couldn’t do it. In Luke’s version (17:5-6), the disciples directly asked Jesus to increase their faith.

In both cases, the disciples seemed focused on the quantity of faith. Jesus’s response with the mustard seed metaphor redirected their understanding.

 

WHAT’S SO SPECIAL ABOUT MUSTARD SEEDS?

In first-century Palestine, the mustard seed was known for being remarkably small, yet from this minuscule beginning comes a plant that can grow to 10 or 12 feet tall. Jesus’s audience would immediately grasp both aspects of this metaphor—its smallness and its remarkable growth potential.

 

THE KINGDOM CONNECTION

Interestingly, this isn’t the only time Jesus used the mustard seed as a metaphor. In Matthew 13:31-32, He says, “The kingdom of heaven is like a mustard seed, which a man took and planted in his field. Though it is the smallest of all seeds, yet when it grows, it is the largest of garden plants and becomes a tree, so that the birds come and perch in its branches.”

This parallel helps us understand Jesus wasn’t just talking about individual faith but connecting it to the larger work of God’s kingdom. Just as the kingdom grows from small beginnings to encompass all nations, genuine faith—however small—participates in God’s expansive work.

 

FAITH LIKE A MUSTARD SEED: A REFORMED PERSPECTIVE

From a Reformed theological perspective, faith isn’t about human achievement but about trust in God’s promises and character. As Ephesians 2:8-9 reminds us, “For by grace you have been saved through faith. And this is not your own doing; it is the gift of God.”

True faith isn’t measured by its emotional intensity but by its object—the trustworthy God who fulfils His promises according to His perfect will and timing.

 

MOUNTAINS THAT MOVE: DISPELLING MISCONCEPTIONS

Perhaps no aspect of Jesus’ teaching has been more misunderstood than His statement about moving mountains. This metaphor has often been distorted into a form of spiritual manipulation—as if faith were a force we can harness to manifest our desires or bend reality to our will.

This isn’t at all what Jesus meant. In Reformed understanding, faith isn’t a power we wield to accomplish whatever we want. It’s a trust in God that aligns our will with His. Mountains move not because we command them to, but because God, in His wisdom and timing, chooses to act in accordance with His purposes.

When Jesus speaks of mountain-moving faith, He’s not establishing a formula for getting what we want. He’s describing a relationship of trust where we submit our desires to God’s sovereignty, believing He will work all things together for good according to His plan.

The disciples couldn’t cast out the demon not because they lacked a certain quantity of faith, but because they were relying on their own abilities rather than God’s power working through them according to His will.

 

FAITH LIKE A MUSTARD SEED: THE GROWTH DIMENSION

While even small faith can be effective because of who God is, Jesus intends for our faith to grow. Just as the mustard seed grows from tiny to substantial, our faith develops over time through God’s nurturing work.

In 2 Thessalonians 1:3, Paul writes, “We ought always to give thanks to God for you, brothers, as is right, because your faith is growing abundantly.” This growth isn’t self-generated but comes through God’s work in our lives through His Word, His Spirit, and the community of believers.

 

FAITH AS A BLESSING TO OTHERS

Just as the grown mustard plant becomes a place where “the birds come and perch in its branches,” mature faith becomes a blessing to others. When our trust in God grows, it not only transforms our own lives but creates a shelter where others can find encouragement and witness God’s faithfulness.

This communal aspect of faith aligns with the Reformed emphasis on covenant community. Our faith, given by God and growing through His work, becomes part of how He extends His kingdom blessing to the world around us.

 

FAITH LIKE A MUSTARD SEED: WHAT THIS MEANS FOR US TODAY

If we feel our faith is weak, Jesus’ teaching offers profound encouragement. The effectiveness of our faith doesn’t depend on our ability to conjure up complete certainty. It depends on the trustworthy God in whom we place our faith.

At the same time, we must invest to grow our faith—not to manipulate outcomes, but to deepen our trust in God’s perfect will. We nurture this growth through Scripture, prayer, worship, and community.

 

CONCLUSION: SMALL FAITH, SOVEREIGN GOD

The mustard seed metaphor ultimately redirects our focus from ourselves to God. It’s not about measuring the size of our faith or using it as a tool to get what we want. It’s about trusting in God’s sovereign purposes and aligning our hearts with His will.

In the Reformed understanding, this perfectly aligns with the principle of soli Deo gloria—glory to God alone. Our faith, whether small or great, is not about our power but about our trust in God’s power, wisdom, and perfect timing.

So let’s take heart. Our mustard seed of faith, placed in the hands of an almighty God, is more than enough to face whatever mountains stand before us. And as we walk with Him, that faith will grow—not so we can accomplish more, but so we can know Him more fully and be a channel of His blessing to others.

 

FAITH LIKE A MUSTARD SEED: RELATED FAQs

How do major Reformed scholars interpret the “faith like a mustard seed” passage? John Calvin emphasised Jesus wasn’t criticising the quantity of the disciples’ faith but their failure to exercise the faith they had. Charles Spurgeon taught that even small faith is effective because it connects us to an omnipotent God, not because of anything within us. Contemporary Reformed theologian RC Sproul highlighted the passage teaches dependence on God’s work rather than our spiritual achievements.

• Does “moving mountains” refer to literal physical miracles or something else? Most Reformed interpreters understand “moving mountains” as a metaphorical expression for overcoming seemingly impossible obstacles according to God’s will. While God certainly can perform physical miracles, the emphasis is on His power working through our trust rather than on spectacle. This interpretation aligns with how mountains often symbolise obstacles or difficulties throughout Scripture.
• How does the prosperity gospel interpretation of this verse differ from the Reformed view? Prosperity teachers often interpret this passage to mean that enough faith guarantees desired outcomes like wealth, health, or success—essentially making faith a tool to receive blessings. The Reformed view rejects this, emphasising that faith isn’t about manipulating outcomes but trusting God’s sovereignty even when He doesn’t remove our “mountains.” Reformed theology prioritises God’s glory and purposes over our comfort or desires.
• Does “faith like a mustard seed” contradict Reformed teaching about God’s sovereignty? Not at all—it actually reinforces it. The Reformed emphasis on God’s sovereignty clarifies that faith’s power comes from its object (God), not from the believer. Faith doesn’t make things happen; God does, according to His wise purposes. The mustard seed metaphor teaches us humble dependence on God’s work rather than confidence in our spiritual achievements.
• How do we reconcile the “smallness” of mustard seed faith with James’ warnings against doubting? James 1:6-8 warns about double-mindedness and doubting, which may seem to contradict the idea that small faith is valuable. The key distinction is between genuine faith (however small) and vacillating unbelief disguised as faith. Even small faith is single-minded in its trust, while double-mindedness doesn’t trust God at all. Instead, it constantly shifts between belief and unbelief.
• How does the Reformed tradition understand faith’s growth from “mustard seed” size? The Reformed tradition views growth in faith as primarily God’s work through the means of grace—Scripture, prayer, worship, and community. Unlike some traditions that emphasise human effort in growth, Reformed theology sees faith’s development as part of God’s sanctifying work. We participate in our growth, but the increase ultimately comes from God through His Spirit’s work.

How does “faith like a mustard seed” relate to assurance of salvation in Reformed theology? Reformed theology distinguishes between the essence of faith and the assurance of faith. Even “mustard seed” faith in Christ is saving faith, though it may lack full assurance. The smallest genuine faith in Christ’s finished work is sufficient for salvation, not because of the faith’s strength but because of Christ’s sufficiency. As faith grows, assurance typically grows too, while salvation depends on Christ’s work, rather than on the size of our faith.

 

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