Hebrews 10:1-4 (ESV)
For since the law has but a shadow of the good things to come instead of the true form of these realities, it can never, by the same sacrifices that are continually offered every year, make perfect those who draw near.  Otherwise, would they not have ceased to be offered, since the worshipers, having once been cleansed, would no longer have any consciousness of sin?  But in these sacrifices there is a reminder of sin every year.  For it is impossible for the blood of bulls and goats to take away sins.
Where there is forgiveness, there must be blood, but not just any old blood. The sacrifices of the Old Testament are kind of funny. I would not say they were merely symbolic. I do think there was something going on there. Yet there was symbolism there, and they were but a shadow of good things to come. They could of course not make perfect those who drew near. Yet this worship was honored by God, and forgiveness of sins, in light of Christ’s sacrifice to come, was communicated through these as means of grace. Those sacrifices could not make perfect. That statement hints at something. It quietly screams, but there is a sacrifice that can! The blood of bulls and goats may not take away sins, but the blood of the Lamb of God certainly does.