In Mark 4, we get various parables about preaching and the Kingdom of God. A lot of these are quite well known, especially the first, which is the Parable of the Sower. The interesting thing is, though, that other than the initial planting in each of the parables, the farmer does not do much else until harvest.
First, in the Parable of the Sower, the farmer only does that. He casts the seed. The rest of what happens is not really due to any effort on his part. The destruction of the seed is not because of faulty action of the farmer; there is no judgement on him for where his seed lands. Then the seed that does produce the crop does so because of the soil, not the efforts of the farmer. Even the multiplication of fruit seems arbitrary. Jesus says that some seeds produce crop thirty times the original, some sixty, some one hundred. What Jesus doesn’t tell us is the reason. He doesn’t say, because the farmer was diligent in his weeding, watering and fertilising. It just says the seed that fell on good soil produced crop of some number.
In another parable within this chapter, it seems to be making this point more explicitly. Again it uses an analogy of seeds. Verses 27-28 says,
Night and day, whether he sleeps or gets up, the seed sprouts and grows, though he does not know how. All by itself the soil produces grain—first the stalk, then the head, then the full kernel in the head.
The passage literally tells us that it does not matter what the farmer does. The farmer could rest or toil, but the seed, which symbolises the Kingdom of God here, grows regardless. The farmer does not even know how it grows; we, if we are honest with ourselves, don’t know how the Kingdom of God grows either. The seed produces crop all by itself.
Of course, that does not mean that God does not use us and that we do not have a role in spreading the gospel. (This has been used as an argument against mission; it’s up to God not us.) But what it does tell us is that it is not under our control. So I don’t know why some churches are number obsessed when the Bible literally says, sometimes it’s thirty, sometimes it’s one hundred but there is no reason. Basically, our job is to sow the seeds. Then we watch as God allows his Kingdom to take root and to grow. And what a marvellous miracle that is.