Did the Old Testament Day of Atonement take away sin?

Les teaches that the word "atonement" as used in the Old Testament was a misnomer, not the appropriate word for the Day of Atonement. Even though the high priest did everything exactly right and offered the blood of the sacrifice on the Holy of Holies and on the mercy seat, it never took away a single sin. It was simply a stopgap waiting for the coming of Christ. It should have been a word about covering, or sweeping under the rug, which is what God was doing with the sins of the Old Testament believer. He swept them under the rug until the true atonement was finalized when the blood of Christ was shed. Then all that stuff under the rug was atoned for, taken away, and forgiven.