26 Jesus said, “God’s Kingdom is as if a man should cast seed on the earth, 27 and should sleep and rise night and day, and the seed should spring up and grow, he doesn’t know how. 28 For the earth bears fruit: first the blade, then the ear, then the full grain in the ear. 29 But when the fruit is ripe, immediately he puts in the sickle, because the harvest has come.”

30 He said, “How will we liken God’s Kingdom? Or with what parable will we illustrate it? 31 It’s like a grain of mustard seed, which, when it is sown in the earth, though it is less than all the seeds that are on the earth, 32 yet when it is sown, grows up, and becomes greater than all the herbs, and puts out great branches, so that the birds of the sky can lodge under its shadow.”

33 With many such parables he spoke the word to them, as they were able to hear it. 34 Without a parable he didn’t speak to them; but privately to his own disciples he explained everything.

Mark 4:26-34 - World English Bible

In these verses from Mark, Jesus used two agricultural analogies to address the importance of evangelization viz-a-viz the Kingdom. The first parable likened the evangelist to a farmer sowing seed. Just as the farmer spread grain on the soil, so did the preacher God 's word. Neither could take credit for growth; that miracle belonged to God alone. In the end, they could only gather in the crop, the farmer into the silo, the evangelist in the assembly of God's chosen.

If the first parable focused on the activity of the one spreading the word, the second told of the miracle itself. The Kingdom would begin, not with an explosion, but with a whisper. Like the growth of a tiny mustard seed, God's realm would expand until it gave comfort to believers (like birds lodging under its shadow). Notice two items about this analogy that could have surprised Jesus' audience. First, the origin of the Kingdom was almost imperceptible; the silent way it would begin flew in the face of many who expected the Kingdom to start after a great battle in which Jewish forces would defeat their enemies (i.e., the Romans) and, so, establish a new empire with Jerusalem as its capitol. Secondly, the growth of the Kingdom would reach beyond any parochial interests and would implicitly become universal; the size of the Kingdom could not be limited by a particular person or nation.

In the end, Jesus left the meaning of these parables to the imagination of his audience, but explained their import to his followers.

How do you envision the Kingdom?