The Leaven of the Kingdom
It [the kingdom] is like leaven, which a woman took and hid in three measures of meal, till the whole was leavened.
The Leaven or Yeast Analogy
The analogy of leaven, or yeast, is used in several applications in the Scriptures. In Mark 8:15, Jesus warned His disciples to beware of the leaven of the Pharisees and the leaven of Herod, which, in a broad sense, refers to the leaven or yeast of false religion and the leaven of worldliness. Also, the Apostle Paul likened sin in the church to leaven, as he rebuked the Corinthian Church for allowing it in their midst, saying that a little leaven leavens the whole lump or loaf?
The Kingdom of Heaven
The point in these analogies is that we are affected by what we expose ourselves to. Jesus likens the kingdom of God to leaven. He also said that the Kingdom of Heaven is within you. When we put the word of God within us, it changes us in a godly way. Yeast placed in flour creates a change in it. It causes it to rise, and adds a unique flavor to it. We should be cautious, and make sure we are putting the right leaven within us, the leaven of exposing ourselves to the things of the kingdom of God. The more we do that, the more the kingdom will be in us.