Mark 4:30–32 NIV
Again he said, “What shall we say the kingdom of God is like, or what parable shall we use to describe it? It is like a mustard seed, which is the smallest of all seeds on earth. Yet when planted, it grows and becomes the largest of all garden plants, with such big branches that the birds can perch in its shade.”

The parable is not about the seed, but the growth process from small to large over time.

God sent His Son into this world. He planted the Lord Jesus in the insignificant soil of a backwater province of Rome called Israel. He grew up there; He lived there and He died there. He was resurrected their.

In the beginning there was just Jesus and a few ragtag followers. His followers consisted of some uneducated fishermen, a few revolutionaries, some women and a traitor. By the time the Day of Pentecost came around, there were still just 120 devoted followers of the Lord, Acts 1:15. It wasn’t many days until the church in Jerusalem is said to have numbered some 50,000.

Matthew 13:33 NIV
He told them still another parable: “The kingdom of heaven is like yeast that a woman took and mixed into about sixty pounds of flour until it worked all through the dough.”

Yeast is a small, micro-organism. Spreads throughout the dough. Transforms, changes, making the batch something other than it was. It adds potential

Yeast is not about taking over or controlling, but quietly (unobtrusively, subversively?) expanding influencing.

Positive effect.
1. The Kingdom does not come to externally conquer and rule over the world.
2. The Kingdom comes to each individual where they are to transform them from the inside out and spread like leaven, to spread throughout the world so that, instead of being converted, it is transformed.

Not to huddle up, but to spread out. Not to take, but to give. Not to press down, but to expand.

The Kingdom grows from one small seed and transforms the world.