Most of us understand that leaven (or yeast) is an agent used in baking to help bread to rise. If anyone has ever baked bread before, you will understand the process. You mix a very small portion of active yeast into flour and after kneading it, you give it time to rise, often to double its size. Yeast is a powerful agent and we know its power in that a small portion impacts the entire structure of a whole loaf of bread. It is in the illustration of leaven that I find it very difficult not to see its application for Christians as we face the turmoil of this year’s election.

The New Testament mainly speaks of the power of ‘leaven’ as illustrations of negative influence, but there is also an example where it is a powerful picture of Christian optimism. Let’s start with the negative. In all three synoptic gospels (Matthew, Mark and Luke) Jesus has conversations with his disciples about the Pharisees and uses the picture of leaven. He tells his disciples to beware of the leaven of the Pharisees (Matthew 16:6, Mark 8:15, Luke 12:1). What he means by this is that the teaching and influence of the Pharisees is that which easily permeates the entire population of Israel who look to them as leaders. Their focus on the rabbinical laws, good works, reputation, and confidence in the flesh is an influence that spreads like leaven in bread. Pharisaical influences spread like an atmosphere of self-righteousness. The Pharisees were all about being Jewish and their goal was to maintain their Jewish culture and nation that was under the continual threatening influence of Roman rule. They were all about pointing the people of Israel to keeping Jewish traditions and rules and protecting their culture from gentile influence. To be leaven is to have an influential presence within the entire demographic in which you enter or belong. In this way, the Pharisees were leaven.

Jesus warns his disciples about the leaven of the Pharisees because these leaders influence a whole community of people away from what really matters. The whole thrust of the Jewish Scriptures promise and foreshadow the coming of a Messianic King who is to be the Savior of God’s people and rule on the throne of David forever. Instead of focusing on the clear signs of Jesus and the hope of salvation, the Pharisees rejected Jesus and placed the hope of the people in their own works, rituals and “Jewishness.” The warning from Jesus is that any influence that seeks to put people’s confidence in our own worldly agendas rather than God’s great saving purpose in Christ is a leaven to beware of.

Paul uses leaven in a similar way. In 1 Corinthians 5, Paul uses the illustration about leaven in warning about how immorality can spread in the church. In Galatians 5:7-9, however, we find much the same discussion from Paul that Jesus has with his disciples. In writing to the churches of Galatia, Paul warns them about a dangerous Jewish element that had come among them to take their hope and confidence away from Christ’s substitutionary atonement for sin and to place it on the works of their own flesh. They were influencing the Galatians toward self-righteousness rather than Christ’s righteousness. They were putting confidence upon their own work in the world rather than Christ’s eternal work in the cross and resurrection. Paul said, “You were running well. Who hindered you from obeying the truth? This persuasion is not from him who calls you. A little leaven leavens the whole lump.”

In every negative use of the illustration of leaven, the New Testament makes it clear that we should fight against every influence that has us placing confidence in our own works and outcomes in this world to find hope. Throughout the gospels and the epistles, God wants us to know that hope is only certain and eternal when it is found in Christ alone and in putting all our trust in his completed work of substituting himself for us to completely atone for our sin to reconcile us to God. Our justification before God relies on Christ. Our ongoing sanctification is in Christ and our hope and confidence for all eternity is in Christ. The moment anyone places their hope in life in any other earthly influence is the moment true eternal hope is forgotten or lost.

There is one other use of the word leaven in the New Testament and it is as optimistic as it could possibly be. When Jesus was teaching in parables to describe his kingdom, he said, "The kingdom of heaven is like leaven that a woman took and hid in three measures of flour, till it was all leavened." (Matthew 13:33). In this example, Jesus is not just talking about the influence of an ideology, he is talking about the actual growth of his kingdom. Jesus wants us to know that his kingdom is like leaven. Those who are in Christ know that compared to the powers this world, the reign of Christ and his church seems to be small and insignificant. In reality, this small leaven in the world is growing and spreading across the globe as the great reigning Kingdom of Heaven. Another way Jesus said this was when he told his disciples that he was building his church and the gates of hell would not prevail against it.