The Mustard Seed

Many of the parables of Jesus were powerful tools used to illustrate an aspect of the Kingdom of Heaven. But these tools did more than illustrate. They were also provocative, divisive, and even  offensive, forcing the crowds to take a step forward or a step back. But how is the Kingdom of Heaven similar to wheat in a field, yeast mixed in dough, or a mustard seed planted in the ground? And why would the crowds have been offended by these parables?