The parable of the mustard seed is contained in each of the three synoptic gospels with the Gospel of Matthew giving the most peripheral information which appears in the middle of two other parables which cover the same subject namely the nature of the kingdom of heaven. It appears alongside the parable of the "weeds among the wheat" and the Parable of the "yeast".
Jesus said how can I describe the kingdom of God? What story should I use to illustrate it? It is like a mustard seed planted in the ground. It is the smallest of all seeds but it becomes the largest of all the garden plants. It grows long branches and the birds can make nests in its shade. Jesus often told parables in public but explained them later to his disciples in more detail. This parable has many common elements. Firstly it is an analogy as to the kingdom of heaven. By implication the story is about a man who sows and the field in which he sows is the world. The seed is seen as the word of God and its effect. We note that there is also growth and spreading and the birds that make nests in its branches represent those who need shelter.
The Mustard seed is the smallest of all seeds and the plant itself is very large and in the Middle East it grows big and is very invasive. Like our faith it can have small beginnings but something that can grow big and which spreads throughout society. We can also use the parable as an analogy for the Church. Jesus can be seen as the sower and the plant becomes a source of food, rest and shelter in much the same way that God becomes a source of spiritual food for us, a shelter when life gets tough, a place where we can find protection and rest. We like the birds can also reside in its branches and we are to take advantage of all the good things produced by the food so that we can be changed by residing in the mustard bush.
The parable of the mustard seed can be seen as an encouragement, a prediction and a warning. Jesus uses pictures from his immediate environment that were common in his day but which we are also able to understand 2000 years later. These include lamps and light, water, the vine, sheep as well as seed. Jesus uses seed a great deal in his teachings and like a seed grows we too are to grow spiritually and be part of the kingdom of God. The kingdom has indeed grown from eleven frightened disciples to approaching 2 billion people across the globe who identify in some with Jesus.
Readings- Matthew 13:31-32 Mark 4:30-36 Luke 13:18-19