Therefore let us keep the feast, not with the old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth.
Listen to the "Verse by Verse" episode covering this scripture.
The apostle Paul wrote more than 20 years after Christ’s death that this mostly gentile congregation in Corinth should “keep the feast” of Unleavened Bread.
From the analogy he uses here, it is clear the members were well acquainted with the removal of physical leaven for that week, and he wanted them to think more deeply about the spiritual lessons of replacing sin with godly thoughts and actions.
Study more about the meaning of this festival in “The Feast of Unleavened Bread: Pursuing a Life of Righteousness.” Read about the meanings of all seven festivals of God in “Festival Meaning: What Are the Meanings of Each of God’s Festivals?”