Blood and yeast

“Do not offer the blood of a sacrifice to Me along with anything containing yeast.” Exodus 23:18
Many people who start reading the Bible from Genesis, get to about Exodus 19 and then lose interest – most of Exodus, Leviticus, Numbers, and Deuteronomy are rule after rule concerning social justice, ceremonial procedures, instructions for sacrifices, the tabernacle, and the like. It’s tempting to skip over these sections if you’re not Jewish. But as with all things, these books are in the Bible because they show us truths about Christ.
Why would God tell the Israelites not to offer yeast and blood together? We need to understand the symbolism being used here. In Lev. 17:11 we read, “For the life of a creature is in the blood, and I have given it to you to make atonement for yourselves on the altar; it is the blood that makes atonement for one’s life.” In the Old Testament, the life-blood of animals was offered as a substitute to cover the sin of a person, sin that required their life to be ended. The ultimate example of this, of course, is the death of Christ on the cross for our sins, shedding His own blood for us.
So what about yeast? Throughout the Bible, yeast is used as a symbol of sin. If yeast is added to dough, it ferments and causes the bread to be puffed up. You don’t need much yeast; it will spread and multiply until it has permeated the whole lump of dough.
So what God is saying here is this: the blood of the sacrifice offered must be without sin. This is beautiful symbolism of our Saviour: He had to be without sin. Otherwise, He could not have redeemed us; He would have died for His own sin.