How is the blood of Christ like the blood on the doorposts in Egypt for our protection?
The blood of Christ provides the same protective security as the Passover blood in Egypt. Just as the death angel could not touch the firstborn where blood was on the door, those who have Christ's blood applied by faith cannot be touched; no power can separate them from God's love.
Les teaches that because God lost us when Adam fell, He must redeem us, and He redeems with blood; it is the only thing God can use to purchase mankind's redemption. Paul shows Christ Jesus was sent to be a propitiation through faith in His blood, and the only way to experience that redemption is putting your faith in the blood of Christ. Paul took us back to the Passover night in Egypt because it is the same setting: just as the Jewish family in Egypt was safe and the death angel could not touch the firstborn because of the blood on the door, so also those who have had the blood of Christ applied cannot be touched. Les connects this to Romans 8, where believers are more than conquerors through Him who loved us, and nothing—death, life, angels, principalities, powers, things present, things to come, height, depth, or any other creature—can separate us from the love of God in Christ Jesus. Why? We are under the blood, and no power on earth or in heaven can take us from under that blood protection. As surely as the Israelites were safe in Egypt, we are safe today.