He told them still another parable: "The kingdom of heaven is like yeast that a woman took and mixed into a large amount of flour until it worked all through the dough." Matthew 13:33
Whenever yeast was used in story lines during Jesus' time, it almost always carried the weight of evil, the sense of being opposite of what God would want. Jesus himself said, "Beward of the yeast of the Pharisees". The view was that yeast was like corruption. It starts small, but invisibly works itself through the dough in no time.
So when Jesus said the above statement, his audience would be shocked. The kingdom of God is corruption? How can this be?
Then when you think about it...the way of God is corruption to the way of hate, racism, genocide, evil and sin.
Many commentators think Jesus was making a seriously political statement here.
So, my friends, how can we get corrupted?