He said therefore, “What is the kingdom of God like? And to what shall I compare it? It is like a grain of mustard seed that a man took and sowed in his garden, and it grew and became a tree, and the birds of the air made nests in its branches.”
Faith was described, by Jesus, as capable of moving mountains upon being the size of a mustard seed. Here is yet another mustard seed comparison: the kingdom of heaven is like a mere mustard seed, developing into a tree able to house many creatures.
Paul once described his work of evangelism as sowing, while his fellow workers watered. However, he stated it was God himself who causes growth. Somewhere, sometime, a mustard seed was sown into someone, watered, and the faith began bearing fruit as the Lord caused growth.
Our kindness spreads, for it is written in John 13:35, ‘” By this all people will know that you are my disciples, if you have love for one another.'”
Therefore, the kingdom of God is as a tiny mustard seed, a mustard seed of faith, sown into one (into us Believers) and grown into a mustard tree. All those surrounding are able to tell if we are followers by the love we contain for one another, and therefore, our work of evangelism is aided. People are drawn to the kingdom and it spreads, growing and attracting many creatures (new Believers).