Why was blood shed from sacrificial animals after Adam believed?
Because Adam believed God, blood was shed from sacrificial animals to provide a covering. It covered the physical body and pictured a spiritual garment, hiding old Adam and pointing to the imputed righteousness of God given to believers, as later described in Romans 3 and Isaiah 61.
Les explains that because Adam had the ability to believe what God said, blood was shed from the sacrificial animals. This was not merely a physical covering; God also clothed Adam with a spiritual garment that hid old Adam and gave him the imputed righteousness of God. Les teaches that this is the same imputed righteousness and covering seen when God clothed Isaiah in Isaiah 61:10 and clothes a believer in Romans 3. Isaiah rejoiced because he was clothed with the garments of salvation, not because of wealth or sheep.