Christ's sacrifice had to be made only one time; it was sufficient to pay the penalty for all of man's sins for all eternity. All the sacrificial law did was foreshadow Christ's sacrifice, which is why it was a reminder and a schoolteacher. It did not define sin, unless the offerings themselves were done wrongly.
Those temporary laws did not pertain to murder, stealing, Sabbath breaking, idolatry, lying, or any of the Ten Commandments. They are now, therefore, set aside because sin has been effectively covered in the sacrifice of Jesus Christ.
The theme of the book of Hebrews is better: Christ is better than angels. The gospel given to us is better than that given under the Old Covenant. Christ is greater, better than Moses and Aaron. The New Covenant is better, greater, superior to the Old Covenant. The sacrifice of Christ is greater, better, superior to the sacrifices under the Old Covenant.
The theme, then, through much of chapters 9 and 10, is that we replace the old with the new. We replace the inferior with a superior, the temporary with the permanent.
John W. Ritenbaugh
The Covenants, Grace, and Law (Part Seventeen)
Jeremiah 31:34 foretells that under the New Covenant, God would not remember sins and lawless deeds. Simply put, sins are not remembered because they have been borne to the “land of forgetfulness.”
The author then takes the explanation a step farther, showing that once remission of sin has been accomplished, there is “no longer an offering for sin.” That is, the role of the azazel—the second part of the compound offering for sin (Leviticus 16:5)—has already been fulfilled! We already have remission of sins; there is not a future fulfillment of any sin offering that those who are already under Christ's blood should be waiting for.
David C. Grabbe
Who Fulfills the Azazel Goat— Satan or Christ? (Part Three)