But when it is sown, it grows and becomes the greatest of all the garden plants and puts out great branches, so that the birds of the sky can nest under its shade.”
Here the emphasis of the parable moves from smallness to greatness. The mustard seed, though small, later becomes large and full of branches. In this way Christ shows that the kingdom of God may at first be unnoticed, but its final impact is broad and far-reaching. The birds dwelling under its shade shows protection and spaciousness. This can also recall the prophetic images where the nations find refuge under the branches of a great tree (Ezekiel 17:23). Thus the kingdom not only grows, but becomes a place of blessing for others. Likewise the Church of Jesus Christ, which began with a small group, by the will of God was to spread among many nations and become the good news of salvation for many.