⭐WEB · Matthew 17:20
What does Matthew 17:20 mean?
"He said to them, “Because of your unbelief. For most certainly I tell you, if you have faith as a grain of mustard seed, you will tell this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible for you."
— Matthew 17:20 (World English Bible)
Surrounding context
Jesus answered, “Faithless and perverse generation! How long will I be with you? How long will I bear with you? Bring him here to me.”
Jesus rebuked him, the demon went out of him, and the boy was cured from that hour.
Then the disciples came to Jesus privately, and said, “Why weren’t we able to cast it out?”
He said to them, “Because of your unbelief. For most certainly I tell you, if you have faith as a grain of mustard seed, you will tell this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible for you.
But this kind doesn’t go out except by prayer and fasting.”
While they were staying in Galilee, Jesus said to them, “The Son of Man is about to be delivered up into the hands of men,
and they will kill him, and the third day he will be raised up.” They were exceedingly sorry.
Explanation
This verse comes from an exchange between Jesus and his disciples after they had failed to cast a demon out of a boy who was suffering from seizures. The disciples, embarrassed and confused, pulled Jesus aside and asked him privately why they could not do what he had commissioned them to do—after all, Jesus had already given them authority over unclean spirits earlier in his ministry. Jesus' answer is direct and unflinching: their failure was not due to a lack of technique or formula, but to unbelief. He then adds this teaching about faith the size of a mustard seed, using a comparison his listeners would immediately grasp, since the mustard seed was proverbial in Jewish culture for being remarkably small yet growing into something large.
The Gospel of Matthew was written primarily for a Jewish-Christian audience, likely to demonstrate that Jesus is the promised Messiah and to instruct new and struggling believers in how to live under his authority. This particular episode falls right after the Transfiguration, where Peter, James, and John witnessed Jesus' divine glory, while the remaining disciples were left below dealing with a desperate father and a tormented son. The contrast is important: even those who had seen incredible things could still stumble when left to act in ordinary ministry, showing that faith, not spectacle, is the real issue at stake.
Theologically, Jesus is not saying that quantity of faith is the key—he's saying that even a very small amount of genuine faith, rightly placed, is powerful because of the object of that faith: God himself. The mustard seed is small
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