Jesus wants his disciples to be comfortable with a certain level of mystery that accompanies God’s work. Consider this obscure comparison:
“The kingdom of God is as if a man should scatter seed on the ground. He sleeps night and day, and the seed sprouts and grows; he knows not how. The earth produces by itself, first the blade, then the ear, then the full grain in the ear. But when the grain is ripe, at once he puts in the sickle, because the harvest has come”(Mark 4:26-29).
In describing the work of a farmer, Jesus focuses on the man’s ignorance. He plants the seed, which sprouts and grows. “He knows not how.” This does not mean that we cannot learn some things by studying crop science, but that there is a mystery associated with the whole process of botanical growth. It does not rely on man’s ingenuity. Man scatters seed. Then he sleeps. And when the grain is ready, he reaps.
This is the nature of the kingdom of God. How God works out his reign, advances his kingdom, and reaches people with the message is often a mystery to us. While we are comfortable with the idea of God’s work being mysterious in realms where we have little role (such as the prenatal development of a child), it is harder when we have a front-row seat and responsibility. It is harder when we are the farmer.
“He knows not how” means that we won’t be able to perfectly engineer kingdom growth. It is not about methods and action plans. We prepare ourselves and plant seeds, then we let God do his work. And when the time is right, we put in the sickle and reap.
There is mystery surrounding evangelism and church growth. There is mystery about exactly how character is formed—whether in mature Christians, new converts, or children (Paul calls it the “fruit of the Spirit,” Gal 5:22). There is mystery in the idea of providence—how precisely God acts to care for his people in everyday life. God keeps working, but we “know not how.”
Our lack of explanation, though, doesn’t mean that we are unaware of our responsibility. The lesson is to follow Jesus in patient trust—and to have the humility to give God the glory for doing amazing things in ways that we “know not how.”