The Parabel of the Mustard Seed is about the growth of Christianity.
Parable of the Mustard Seed
Another parable He put forth to them, saying: "The kingdom of heaven is like a mustard seed, which a man took and sowed in his field, Which indeed is the least of all the seeds; but when it is grown it is greater than the herbs and becomes a tree, so that the birds of the air come and nest in its branches."
Parable of the Leaven
Another parable He spoke to them: "The kingdom of heaven is like leaven, which a woman took and hid in three measures of meal till it was all leavened."
All these things Jesus spoke to the multitude in parables; and without a parable He did not speak to them, that it might be fulfilled which was spoken by the prophet, saying:"I will open My mouth in parables; I will utter things kept secret from the foundation of the world."
Then Jesus sent the multitude away and went into the house.
These are often called the "kingdom parables" because each begins with the phrase "The kingdom of Heaven is like."
The parable of the mustard seed shows how the Kingdom of God will have a small beginning, and will grow to become the largest plant in the garden. Jesus predicted the rapid spread of Christianity.
The smallness of mustard seed is later related to faith in Matthew 17:20.
The parable of the leaven shows how Christianity affects the hearts of men. Jesus used the word "hid" to describe how the woman added the leaven. When the word of Christ is hidden in the heart of a believer, it becomes life-changing. God's word changes lives.