Israeli mustard plant

This is my sermon for this coming Sunday, based on the Gospel reading’s parable about mustard.

I have designed it to illustrate two things. The first is how New Testament scholars analyse early Christian texts to shed light on what Jesus said and meant. The second is how this kind of research sometimes challenges earlier views and presents Jesus as a much more radical and exciting character. My main source is John Dominic Crossan’s The Historical Jesus. Crossan’s interpretation is disputed but I find it convincing.

Jesus taught about what he called the Kingdom of God, and encouraged his supporters to do their own teaching. So they repeated his parables and adapted them for different situations. The gospel writers wrote down the versions they knew about, and perhaps adapted them for their own purposes.

The mustard parable is recorded in four gospels: Matthew, Mark, Luke and Thomas. The Gospel of Thomas wasn’t included in the Bible but is an early collection of sayings by Jesus.

It is comparatively easy to work out what each of these authors meant; it’s another matter to work out exactly what Jesus said and meant. Scholars look for clues in the differences between the texts. The texts are at the end of this post.

The seed

The mustard seed is smaller than all seeds in Thomas, the smallest of all seeds in Mark and Matthew. It isn’t. It’s small but lots of seeds are smaller. Poppy is smaller.


In Thomas it falls on the tilled earth, in Mark it is sown on the ground, in Luke it is sown in a garden, in Matthew it is sown in a field. They didn’t normally sow mustard in gardens because it’s one of those plants that spreads. Once you’ve got it you’ll never get rid of it. Here’s the Roman writer Pliny the Elder, writing around the time of Jesus:

Mustard… with its pungent taste and fiery effect is extremely beneficial for the health. It grows entirely wild, though it is improved by being transplanted: but on the other hand when it has once been sown it is scarcely possible to get the place free of it, as the seed when it falls germinates at once.

The size of the plant

In Thomas the seed produces a large branch, in Mark it becomes the greatest of all shrubs and puts forth large branches, in Luke it grew and became a tree, in Matthew it is the greatest of shrubs and becomes a tree.

It looks as though all four gospel writers are making a contrast between the small seed and the large size of the plant. This is clearly the case with Matthew and Luke who describe it as a tree. They seem to be using the story as an image of the Christian church. The Church started off very small, but God makes it grow and grow. This is how many commentators have understood the parable.

It can’t have been what Jesus meant. If it had been, it wouldn’t have been very interesting. Every advertiser of a growing organisation makes this point. We get bored with announcements of profit increases.

When Jesus told his parable, he must have meant something different. He knew about life on the farm. He knew what the mustard plant meant. So did the people he was speaking to. They were mostly farmers, or from farming families.

Normally, Israeli mustard grows to three or four feet high. You can see it at its highest here, about 8 feet. Nowhere else in ancient literature is mustard described as a tree. If Jesus had wanted to contrast the smallness of the seed with the large size of the ‘tree’, there were plenty of real trees which would have made the point much better.

The birds

In Thomas the mustard plant becomes a shelter for the birds of heaven, in Mark the birds of the air can make nests in its shade, in Luke the birds of the air made nests in its branches, in Matthew the birds of the air come and make nests in its branches.

Look at it from the farmer’s point of view. Once you have got mustard in your field you can’t get rid of it. Does it matter? Yes, because birds will nest in it. You sow your seeds, the birds eat them. It’s the last thing you want. The presence of the mustard plant is not to be admired, it’s to be lamented.

You know what it’s like in an unequal society. Every time we go into the shopping centre in Liverpool, as we walk along the pavement we have no choice but to set eyes on all these beggars asking for money. It’s all too easy to think: ‘if only somebody would just get rid of them! We don’t care what happens to them so long as somebody gets them out of the way.’

That was what it was like in Jesus’ day. Jesus’ ministry was mainly to poor and starving people. The Old Testament has lots of rules about what you can eat and how to cook it. People who were desperately hungry were not going to stick to all those laws. They would eat anything they could lay their hands on. Other rabbis disapproved of Jesus for eating the wrong kinds of food in the company of the wrong kinds of people.

Taking all these points into account, it looks as if this parable of the mustard seed was originally Jesus’ way of saying: ‘Ha! We’re like mustard. We’re a nuisance to the powers that be. But we’re here now and they can’t get rid of us!’

As we do our best to follow the way of Jesus, may we always remember that, to God, nobody is a nuisance. Nobody is to be got out of the way. Everybody is a child of God, loved by God, called by God to a fulfilling and holy life.

Here are the texts:

Gospel of Thomas 20:

The disciples said to Jesus: Tell us what the Kingdom of Heaven is like. He said to them: It is like a mustard seed, smaller than all seeds. But when it falls on the tilled earth, it produces a large branch and becomes shelter for the birds of heaven.

Mark 4: 30-32:

He also said, ‘With what can we compare the kingdom of God, or what parable will we use for it? It is like a mustard seed which, when sown upon the ground, is the smallest of all the seeds on earth; yet when it is sown it grows up and becomes the greatest of all shrubs, and puts forth large branches, so that the birds of the air can make nests in its shade.’

Luke 13:18-19:

He said therefore, ‘What is the kingdom of God like? And to what should I compare it? It is like a mustard seed that someone took and sowed in the garden; it grew and became a tree, and the birds of the air made nests in its branches.’

Matthew 13:31-32:

He put before them another parable: ‘The kingdom of heaven is like a mustard seed that someone took and sowed in his field; it is the smallest of all the seeds, but when it has grown it is the greatest of shrubs and becomes a tree, so that the birds of the air come and make nests in its branches.’