For the Lord’s Supper, we use unleavened bread. What is leaven? Leaven is any of several agents used in doughs and batters that cause gas bubbles to form inside the dough to lighten and soften it. A typical leaven is baker’s yeast. When baker’s yeast is added to dough, the yeast grows, feeds on the dough and spreads throughout the whole batch, creating gas bubbles as it grows. This spreading occurs over time and is not instantaneous. Unleavened bread is bread that is made from dough that does not include any leavening agent and therefore there are no gas bubbles to lighten and soften the bread.
The first mention in the Bible of unleavened bread is found in the book of Exodus. God, through Moses, was delivering the Israelites from their slavery in Egypt. They were leaving Egypt in haste; therefore there was no time to prepare bread dough, add the leavening, and let the leavening work its way throughout the dough. The bread eaten had to be unleavened bread. This bread became a symbol of the deliverance from Egypt and the haste in which the deliverance occurred. Exodus 12:14-20 “So this day shall be to you a memorial; and you shall keep it as a feast to the Lord throughout your generations. You shall keep it as a feast by an everlasting ordinance. Seven days you shall eat unleavened bread. On the first day you shall remove leaven from your houses. For whoever eats leavened bread from the first day until the seventh day, that person shall be cut off from Israel. On the first day there shall be a holy convocation, and on the seventh day there shall be a holy convocation for you. No manner of work shall be done on them; but that which everyone must eat — that only may be prepared by you. So you shall observe the Feast of Unleavened Bread, for on this same day I will have brought your armies out of the land of Egypt. Therefore you shall observe this day throughout your generations as an everlasting ordinance. In the first month, on the fourteenth day of the month at evening, you shall eat unleavened bread, until the twenty-first day of the month at evening. For seven days no leaven shall be found in your houses, since whoever eats what is leavened, that same person shall be cut off from the congregation of Israel, whether he is a stranger or a native of the land. You shall eat nothing leavened; in all your dwellings you shall eat unleavened bread.” The feast of unleavened bread is also called the Passover feast. It was during this feast that Jesus instituted the Lord’s Supper; for this reason, we use unleavened bread in our observance of the Lord’s Supper.
The spreading of the leaven within dough is symbolic of some things good and somethings bad. First, look at the good. Matthew 13:33 “Another parable He spoke to them: ‘The kingdom of heaven is like leaven, which a woman took and hid in three measures of meal till it was all leavened.’” The spreading of the kingdom of heaven or the church was like the spreading of leavening in bread dough. When the early church was persecuted, the gospel spread. Acts 8:4 “Therefore those who were scattered went everywhere preaching the word.” In a few short years, the gospel of Jesus Christ was spread throughout the known world, just as leavening spreads through dough.
Leavening can be symbolic of bad things. Matthew 16:5-12 “Now when His disciples had come to the other side, they had forgotten to take bread. Then Jesus said to them, ‘Take heed and beware of the leaven of the Pharisees and the Sadducees.’ And they reasoned among themselves, saying, ‘It is because we have taken no bread.’ But Jesus, being aware of it, said to them, ‘O you of little faith, why do you reason among yourselves because you have brought no bread? Do you not yet understand, or remember the five loaves of the five thousand and how many baskets you took up? Nor the seven loaves of the four thousand and how many large baskets you took up? How is it you do not understand that I did not speak to you concerning bread? — but to beware of the leaven of the Pharisees and Sadducees.’ Then they understood that He did not tell them to beware of the leaven of bread, but of the doctrine of the Pharisees and Sadducees.” Luke 12:1-2 “In the meantime, when an innumerable multitude of people had gathered together, so that they trampled one another, He began to say to His disciples first of all, ‘Beware of the leaven of the Pharisees, which is hypocrisy.’”
The church in Corinth had sexual immorality in their midst and they were proud of it. 1 Corinthians 5:6-8 “Your glorying is not good. Do you not know that a little leaven leavens the whole lump? Therefore purge out the old leaven, that you may be a new lump, since you truly are unleavened. For indeed Christ, our Passover, was sacrificed for us. 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.” Within a church, un-repented sin that is not properly dealt with can spread like leaven within dough. Perhaps one individual sins and nothing is done about it; that might encourage another individual to commit a similar sin and expect nothing to be done either. As a little leaven spreads throughout the whole lump of dough, even so sin might spread throughout the whole congregation. To prevent that from happening, the Corinthians were instructed to “purge out the old leaven”. Even so, today we must exercise church discipline to encourage the sinner to repent and to keep the church clean from sin. We must purge out sins such as malice and wickedness (leavened bread) so that we can exhibit to God sincerity and truth (unleavened bread).
In a similar way, sin in one area of your own life can be like leaven and spread into other areas of your life. When you become aware of any sin in your life, purge it out and don’t let it stay so that sin might not spread within you. Live your life with the unleavened bread of sincerity and truth.