Understanding the Biblical Holy Week (aka Passover Week) helps in understanding Paul’s analogy. (Exodus 12:1-30, Leviticus 23:4-8; Deuteronomy 16:1-8; John 13:1-2, 18:27, 19:14)
Preparations were needed before Passover began. According to tradition, cleaning the location of any yeast was first. “Get rid of the old yeast,” Paul repeats the Mosaic Law (7). Yeast is usually a symbol of sin in the Bible. (Matthew 16:11-12; Mark 8:15; Galatians 5:7-9)
After this, before Passover began, the Passover lamb was killed and prepared (7). Then, Passover began with the meal the evening before Passover day. The Passover lamb, bitter herbs, and unleavened bread (without yeast) were eaten that evening. Passover Day continued until evening the next day.
Jesus is our Passover Lamb who takes away sin. (7, John 1:29, 36) In his death on the cross, Christ fulfilled the true meaning of the sacrifice of the Passover Lamb (Isaiah 53:7). Jesus takes away yeast (sin).
The “Festival” is the Feast of Unleavened Bread, which follows Passover. It lasts for the remainder of the week, symbolizing living the Christian life in holy dedication to God (Romans 12:1-2; 1 Peter 2:5) and not getting involved in such sins as malice and wickedness and incestuous marriages. We are to remain without sin.
Thus, Apostle Paul uses these Mosaic Feasts, just as John the Baptist did, to reveal God’s plan for the church. We are to remain without sin (yeast).

