Without shedding of blood is no remission (Hebrews 9:22).
The central theme of the whole Bible is the shedding of blood for the atonement of sin. For the life of the flesh is in the blood: and I have given it to you upon the altar to make an atonement for your souls: for it is the blood that maketh an atonement for the soul (Leviticus 17:11).
The word atonement is an Old Testament word which means, to cover over. The sins of Gods people were covered over by the sprinkling of the blood of the sacrifice on the mercy-seat in the Holy of Holies, but this had to be repeated year after year. And every priest standeth daily ministering and offering oftentimes the same sacrifices, which can never take away sins (Hebrews 10:11).
The blood of animals cannot take away sin, but the blood of Christ, who is our perfect sacrifice, can. Neither by the blood of goats and calves, but by His own blood He entered in once into the holy place, having obtained eternal redemption for us (Hebrews 9:12). But this man (Christ), after He had offered one sacrifice for sins for ever, sat down on the right hand of God. . . . By the which will we are sanctified through the offering of the body of Jesus Christ once for all (Hebrews 10:12,10). Nor yet that He (Christ) should offer Himself often, as the high priest entered into the holy place every year with blood of others; . . . but now once in the end of the world hath He appeared to put away sin by the sacrifice of Himself (Hebrews 9:25,26).
For the New Testament believer, sins are no longer covered but washed away never to be brought to Gods attention again. But ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus (I Corinthians 6:11).
Therefore, being now justified by His blood, we shall be saved from wrath through Him (Romans 5:9). NPS