Jesus’ referring to the mustard seed as being smaller than all other seeds has often been cited as proof that Scripture is errant—that Jesus was either fallible and made a mistake or that He accommodated His teaching to the ignorance of His hearers and knowingly distorted the truth. But He was not comparing this seed to all other seeds in existence but only to the seeds of garden plants in Palestine. Many seeds, such as those of the wild orchid, are much smaller than the seed of the mustard plant. But of the many plants grown at that time in the gardens and fields of Palestine, the mustard plant has the smallest seeds, just as Jesus said.

When sperma (seed) is used in the New Testament in reference to plants, it is always used of agricultural plants, those intentionally grown for food. And of those plants, the mustard had seeds that were smaller than all other seeds.

Another lesson of the parable of the mustard seed is that the kingdom of heaven will be a blessing to the rest of the world. The tree that grows from the small mustard seed represents the kingdom of heaven, which in the present age corresponds to the church.

When Christians live in obedience to the Lord, they are a blessing to those around them. Individual believers become the source of benediction to nations. And with all their faults, those nations of the world who have been so influenced and who have recognized God’s sovereignty and have sought to build their laws and standards of living on His Word have proved a blessing to the rest of the world in economic, legal, cultural, and social ways as well as spiritual and moral. It is from the teachings of Scripture through Christian witness that high standards of education, justice, the dignity of women, the rights of children, prison reform, and countless other such social benefits have come. Whenever the gospel of the kingdom of God is faithfully preached and practiced, all the world benefits.

The contrast between an unusually small beginning and a large mature plant is the point of this parable. Jesus’ ministry was despicably small in the eyes of many Jews. Nevertheless from this small beginning would come the worldwide kingdom predicted in the Old Testament.

As always, Jesus constructed the parable out of the common experiences of His hearers. In every household the woman responsible for baking would save a piece of leavened dough from a risen batch just before it was baked. When the next batch of dough was mixed, she took the saved piece from the previous batch and hid it in the new, in order that its leaven, or yeast, could ferment the new batch of dough and make it rise.