We see the ‘Scarlet Thread of Redemption’ again clearly in Exodus 29, where God institutes the practice of the ‘Sin Offering’ to the Israelites. Here are His key instructions:
10 “Then you shall bring the bull before the tent of meeting. Aaron and his sons shall lay their hands on the head of the bull.
11 Then you shall kill the bull before the LORD at the entrance of the tent of meeting,
12 and shall take part of the blood of the bull and put it on the horns of the altar with your finger, and the rest of the blood you shall pour out at the base of the altar.”
God specifically labels this as a “sin offering” (verse 14). Why does God introduce it here as part of His institution of the Aaronic Priesthood and the ordination of Aaron and his sons as priests? Because, like all of us, Aaron and his sons were sinners. It was a visual demonstration that they needed their sins to be ‘covered’ (atoned for), which could only be done by the blood of an innocent life being shed in their place. Notice how God instructed them to “lay their hands on the head of the bull” (verse 10) as a symbol of the transferring of their sins to the bull which became their substitute and would bear the penalty for their sins (death).
We’ll find out later (as we read through Levitcus) that these kinds of sacrifices, using animals, were so imperfect and incomplete. All this points us to what the writer of Hebrews wants us to see: “Under the old system, the blood of goats and bulls and the ashes of a young cow could cleanse people’s bodies from ceremonial impurity. Just think how much more the blood of Christ will purify our consciences from sinful deeds so that we can worship the living God. For by the power of the eternal Spirit, Christ offered himself to God as a perfect sacrifice for our sins.” (Hebrews 9:13-14 NLT)