The mustard seed takes time to grow into a tree. It takes years. Likewise, leaven does not cause the dough to rise immediately after being mixed in; rather, it takes time for the leaven to spread throughout the dough.
The reason the Jews could not recognize Jesus as the Messiah is that the kingdom of God they envisioned was radical and visibly expansive. However, the kingdom of God in Jesus' parables is gradual. It has been 2,000 years since Jesus came and ascended into heaven, and the kingdom of God is still unfolding. Like leaven rising over 2,000 years or a mustard seed growing into a tree, the process continues, which is why no one can fully see the kingdom of God.
The kingdom of God that Jesus speaks of is gradual, and this gradual nature can only be seen when one accepts the Word and follows the Holy Spirit.
Excerpt from the sermon by Pastor Lee, Oct 2, 2024.
Luke 13:18-21