Paul says that because of Christ’s Passover sacrifice, “Therefore let us keep the feast (of unleavened bread)–Leviticus 23:4-8, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth.” I Corinthians 5:8
During the feast of unleavened bread, Christians were instructed to put leavening and any leavened product out of their homes. Leaven, which puffs up, symbolizes sin; as we become Christlike, we are to put sin (the way of the world, the “old man”) –Colossians 3:8-11 out of our lives.
Leavening is not sin, just a symbol of it. Eating or not eating leaven does not save us–salvation is the gift of God. God’s instructions for the feast of unleavened bread were given so that by following them we might learn the importance of putting sin out and Jesus Christ into our lives.
Paul also reminded us to keep the feast with the unleavened bread of sincerity and truth. (See also Leviticus 23:6) Eating this unleavened bread represents the Christian’s willingness to accept Jesus Christ into his or her life. “I am the way, the truth, and the life. No one comes to the Father except through Me.” John 14:6. Jesus also said, “I am the bread of life...If anyone eats of this bread, he will live forever; and the bread that I shall give is my flesh, which I shall give for the life of the world.” John 6:48,51
Christ, our Passover, died for us. But as Paul notes in God’s word, that is not the end of our salvation, it is but the beginning. It is Christ’s death that brings us into an on-going relationship with God the Father (see Hebrews 10:19-23). As Paul said, ”...purge out the old leaven, that you may be a new lump.” I Cor. 5:7 We are called by God to be a new lump–a new man–a new creation, in and through Jesus Christ.