In the Bible, the word “yeast” or “leaven” is used to symbolize influence. Just a little yeast added to a large amount of dough influences it, causing it to bubble and rise. But influences can be bad or good. On several occasions Jesus said to beware of the “leaven” or yeast of the Pharisees (legalism), the Saducees (theological liberalism), or the Herodians (worldliness).
But in the Bible in our scripture reading below in Matthew 13:33, Jesus speaks of good influences in the world. When He came the world was influenced by His presence, teachings, crucifixion, and resurrection. And now 2000 years the Kingdom of God has spread around the world. Praise the Lord!
(Matthew 13:33) 33 He told them still another parable: “The kingdom of heaven is like yeast that a woman took and mixed into about sixty pounds of flour until it worked all through the dough.”