Leavening is an agent that causes change, typically through fermentation. The ingredients break down in a biochemical reaction that produces carbon dioxide, which causes expansion. The original ingredients are changed from what they were through a reaction that will keep going as long as there are ingredients that can fuel it. So, leaven spreads.
In its broadest sense, leaven is a symbol of corruption. It includes sin, but it is not limited to sin because it also includes the ideas, philosophies, and approaches that lead to sin. This connects with what we saw in Galatians. The Galatians (and Colossians) were being influenced by philosophies and doctrines that would lead them into bondage. Leavening was corrupting them, and a new slavery would be the result if they didn’t return to Christ.
Here, Paul says a little leaven leavens the whole lump. He uses the same phrase in Galatians 5:9. In the verse that comes right before that, Paul calls the heresy that was corrupting the Galatians a “persuasion.” Paul says, “This persuasion does not come from Him who calls you.” So, leavening can be an idea that persuades us to deviate from the truth, even as our minds may feel like they are expanding.
This fits with the various warnings Jesus gave about leavening. He warned about the leaven of the Pharisees, the leaven of the Sadducees, and the leaven of Herod. In each case, leavening is a symbol for corrupted ideas that lead to a wrong application.
In Matthew 16:12, we find that part of the leaven of the Pharisees was their doctrines, which elevated tradition above the word of God. Another part of their leaven was hypocrisy. They focused more on appearing righteous than being righteous. Jesus said of the Pharisees, “they say, and do not do” (Matthew 23:3). They exempted themselves from the standard they held others to. While they looked good, their self-centeredness and self-generated standard of righteousness made life very difficult for those caught in their orbit.
The leaven of the Sadducees was their corrupted teachings and attitudes, like skepticism, that undermined the essential doctrines of faith. As two examples, the Sadducees denied the resurrection and they denied the existence of angels. That is a significant corruption.
The leaven of Herod is interesting because of the politics of our day. It is not clearly defined, so we have to read between the lines. But from what we know of Herod, his leaven seems to be a worldly pragmatism, and an overall disregard for spiritual truth in favor of power. His corruption seems to include the use of religion for political ends. Herod wouldn’t stop his adoring crowd from likening him to God, and God struck him dead.
Here in I Corinthians 5, Paul uses malice and wickedness as additional types of leaven. Malice is an internal disposition, while wickedness is an outward manifestation. We can tell from the rest of the epistle that these corruptions were affecting the congregation, which is why Paul brought attention to them.
Paul contrasts those with sincerity and truth. Sincerity indicates purity. It means something is not a mixture. Truth here goes beyond simply being factual. It carries the implication of what is genuine and what is real. In the context, it indicates truth that is lived and not simply acknowledged.
Consider, though, that sincerity and truth epitomize the life lived by God in the flesh. He is the unleavened bread of sincerity and truth, the bread of life, the bread that fills us with spiritual life and which contains no malice, wickedness, or other corruption. We cannot generate that sincerity and truth from within—it must come from Him. It is through Jesus living His life in us that we can keep this feast with sincerity and truth.
Verse 7 says the Corinthians are truly unleavened. Paul says it is because Christ is our Passover and was sacrificed for us. Given what the rest of the letter is about, … . . .
It is commonly held that Unleavened Bread is about putting sin out of our lives. And while that is an aspect, if we were to go through all of God's instructions for Unleavened Bread, we would see that His reason and emphasis are different. What God overwhelmingly emphasizes is His deliverance, not our work of avoiding leavening and thus sin (Exodus 12:17; Exodus 13:3, 8-9; 23:15; 34:18; Deuteronomy 16:3).
The overarching reason for that feast, and the reason we eat unleavened bread for seven days, is to remember God's deliverance. When we get to the New Testament, Jesus identifies Himself as the bread of God - the bread of life. He was entirely unleavened.
Further, Paul tells us in I Corinthians 5:8, Therefore let us keep the feast, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth. Christ is the embodiment of sincerity and truth. He is the One who delivered us from this present, evil age, from spiritual bondage, from the power of darkness. And it is through the strength that He supplies that we have the means to overcome sin. And that strength comes from ingesting His word and beseeching Him to live His life in us every day.
The unleavened bread that God says we must eat for seven days represents Christ Himself. To miss eating the unleavened bread of sincerity and truth is to miss out on the divine connection with our Savior. Our minds should rebel at the thought of skipping that.
In the same way, we keep the Feast of Unleavened Bread for seven days by eating unleavened bread each day and not merely avoiding leavening. Consider what neglecting to eat the unleavened bread of life every day would signal to God. The symbols matter.
Ecclesiastes is often part of the reading for Tabernacles, yet this lesson also relates to Unleavened Bread. Unleavened Bread teaches that true satisfaction cannot come from anything physical. Lasting satisfaction only comes from the Bread of Life. To the world, that perfect Bread of Life seems lackluster, and even revolting. Carnal man cannot imagine the benefit of being strengthened by Christ and letting go of sin. Like leavening, sin seems normal. For the unconverted, it is a shock to think about going without.
His final statement here in verse 13 brings in Unleavened Bread: The source of Paul's strength was not himself. It couldn't be. It was Christ, the Bread of Life. It was food that the world would not accept because it seemed to be lacking the ingredients for a fulfilling life. Yet Paul saw it differently. He sought out this Bread because he understood its true worth. As a result, he had strength and he had internal peace and stability, even though outwardly it seemed like he was always buffeted about. The unconverted do not understand this. They believe rejoicing only comes from good times and abundance. Yet God says there can be rejoicing in trials, or when we are abased, or when normally good things are lacking.
