The religious people-controllers, who took every opportunity to criticise Jesus, had very low horizons - they were preoccupied with themselves, their position and what people thought of them.  Their objective was to retain their carefully worked out power hierarchy, so that their authority could continue to dominate people’s lives (Luke 11:46; Luke 11:52).  But the Lord Jesus was so different.  They wanted to bind people to rules, but He wanted to win them to a relationship with God. His purpose was to include them in His kingdom which was going to be far bigger than the rabbis could imagine - it would be populated by believing Jews and Gentiles from every people-group in the world.

By using the analogy of the mustard seed, Jesus identified a well-known tiny seed which had the potential to become a huge tree.  He said that was a picture of the Kingdom of God.  He was, of course, pointing to Himself ... a small living seed which must die in the ground, but which would germinate to form a huge tree which would welcome whoever wanted to rest in its branches.  

That prophecy is still being worked out.  Over a third of the current world population believes in Jesus the Saviour.  They are from every kind of ethnic background, language, religious tradition and cultural lifestyle.  Wherever persecution is most severe, that is where the church grows strongest (Acts 8:1-8).

Whenever Jesus is forbidden, people want Him more; and wherever He is announced people are saved (Romans 10:11-13).  It may take time: it takes time for a small seed to grow into a tree; however, the end result is certain ... a horizon filling, Jesus-worshipping, God-glorifying, world-wide, heaven-high church (Habakkuk 2:14).  So, take courage, do not be ashamed of the gospel, the church, the Bible or the Saviour: because everybody who calls on the Name of the Lord will be saved (Romans 1:16)!