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.'"