The kingdom of heaven is like a mustard seed . . .the kingdom of heaven is like . . .yeast mixed into a large amount of flour . . .Jesus spoke all these things to the crowd in parables . . .so was fulfilled what was spoken through the prophet: I will open my mouth in parables, I will utter things hidden since the creation of the world. ~ Matthew 13:31-35
Jesus did not explain the meaning of the parable of the mustard seed, and the yeast in the large amount of flour. Because of Jesus' silence, these two stories are open to a lot of discussion and interpretation. However, I feel quite sure that Jesus intended all the parables to fit together and give us a multi-faceted understanding of the nature of the kingdom of heaven.
For a mustard seed to grow to the size of a tree, it had to experience supernatural growth. If we go to the scriptures, it is plain to see that in the gospels and in the book of Acts, the kingdom grew explosively and supernaturally. In the gospels, John the Baptist's announcement of the arrival of the king and the kingdom of heaven provoked phenomenal happenings. People from all over Jerusalem, all Judea, and the whole region of the Jordan, flocked to John's message. From the time Jesus began to speak of the kingdom, thousands of people frantically found their way to him. The advance was explosive.
In the book of Acts we see the kingdom advancing exponentially, supernaturally, and spiritually from Pentecost to the last pages of the Acts record. The presence of the kingdom was highly visible and supernatural, just like the mustard seed that grew to the size of a tree. Ever since then, supernatural and highly visible growth of the kingdom has been rare. With the exception of scattered awakenings throughout the centuries, the advance of the kingdom has been slow.
In the parable, Jesus may have given us a hint as to why those epoch advances were so short lived. In the mustard tree sat birds. In Jesus' parable of the sower and the seed -- birds represented the evil one who stole away the seed of God's Word. Is it not safe to assume that the birds in the mustard tree tell us that in the midst of great movements of God -- we are most vulnerable?
Where is the gospel of the kingdom working around you right now? Be aware of the evil that will be lurking in the wings -- whose objective is to steal away the miracle-making Word of God!