The writer of Hebrews stated earlier that the law could make nothing perfect (7:19). The law and its prescribed sacrifices cast but a mere shadow of the good things which were to come in Christ (10:1-10). Those sacrifices which were brought before God year after year could never make those who offered them perfect. Their relationship with God could never be perfect or complete under the law because their sins could never be fully and eternally forgiven. If those sacrifices could have made the worshippers perfectly forgiven before God they would have ceased to be offered. There was always a consciousness of sins, and every year in those sacrifices was a reminder that one was not perfectly and eternally forgiven.
It was not possible that the blood of bulls and goats could have taken away sins. In order for man’s sins to be forgiven, a man must die for their sins. That’s why the perfect Man who was God Incarnate, came into the world. He appeared once at the end of the ages to put away sin by the sacrifice of Himself. Christ was offered once to bear the sins of many! And by that one offering He has perfected forever those who are being sanctified (10:14).