The Gift of the Lamb
Under the Old Testament Law, God’s people were responsible for their own sacrifice. The system was designed to accommodate those of various social classes so no one could say he was incapable of participating.
Yet, there was one sacrifice no human was capable of making: a full atonement for sin. Theologians have used various explanations to describe the inadequacy of the Old Testament sacrificial system to save. Some say the sacrifices offered up before Jesus came to earth were a means of “rolling over” debt. The debt wasn’t erased, but God accepted the sacrifices of His people as a sign of repentance and granted them mercy. Others describe something similar to a shopping cart where the world’s sins were gathered together in a grace basket, to eventually be purchased at the cross.
It is generally assumed the blood of Jesus was retroactive, in that it became the agent by which those who obeyed God in the Old Testament were saved. We may not be able to fully comprehend this arrangement since we are limited by space and time. But we can safely say mankind was incapable of coming up with a sacrifice himself to satisfy the justice of God. The only way we could be saved was for Him to come in the form of His Son Jesus and be both just and justifier. He remained true to Himself, while paying our debt to set us free.