Moses' Teachings with their yearly cycle of sacrifices are only a shadow of the good things in the future. They aren't an exact likeness of those things. They can never make those who worship perfect.
If these sacrifices could have made the worshipers perfect, the sacrifices would have stopped long ago. Those who worship would have been cleansed once and for all. Their consciences would have been free from sin.
Instead, this yearly cycle of sacrifices reminded people of their sins.
(The blood of bulls and goats cannot take away sins.)
For this reason, when Christ came into the world, he said, "'You did not want sacrifices and offerings, but you prepared a body for me.
You did not approve of burnt offerings and sacrifices for sin.'
Then I said, 'I have come! (It is written about me in the scroll of the book.) I have come to do what you want, my God.'"
In this passage Christ first said, "You did not want sacrifices, offerings, burnt offerings, and sacrifices for sin. You did not approve of them." (These are the sacrifices that Moses' Teachings require people to offer.)
Then Christ says, "I have come to do what you want." He did away with sacrifices in order to establish the obedience that God wants.
We have been set apart as holy because Jesus Christ did what God wanted him to do by sacrificing his body once and for all.