Jesus uses two pictures which every Jew would readily comprehend: firstly, the grain of mustard seed was generally considered to be the smallest possible thing in those days in that region. Secondly, we can read in the Old Testament that a common way to describe a great empire was to describe it as a tree and the nations which it had conquered as birds sheltering in its branches. Probably the best known passage is in the book of Daniel 4 v 10-12, where King Nebuchadnezzar, ruler of the great empire of Babylon, was describing a portentous dream he had experienced. So, what does this parable teach us?
1. Don't be daunted by small beginnings. We may often feel that we can hardly effect anything, as small and weak as we are, but everything has to start somewhere and it is our call to do whatever we can, even if it seems to be 'a drop in the ocean'. Hudson Taylor spent much of his life-51 years- in China and brought some people to know the Lord, but look at the effect on China which Christianity is now bringing with estimates of 100 million Christians!
2. It speaks of the Church growing as an empire! It is an empire which embraces many different opinions and under which all nations meet and it began in Israel as small as a mustard seed, just a few dozen followers, and has room for all, no one need be excluded. Churches may put up barriers, but God in Christ has and will tear them down. ''The Father sent the Son to be the Saviour of the WORLD!''