Hebrews 10:4-6 For it is not possible that the blood of bulls and of goats should take away sins. Wherefore when he came into the world, he said, Sacrifice and offering thou would not, but a body have thou prepared me: In burnt offerings and sacrifices for sin thou have had no pleasure. 

‘Not possible that the blood of bulls and of goats should take away sins.’ The Law couldn’t take away sins, make perfect, or purify the heart. Why some religious groups insist on going back under the law in some points is only explainable by 2Corinthians 4:4; 11:14-15; 2Timothy 4:1-4 and 2Thessalonians 2:8-12.

‘Sacrifice and offering thou would not, but a body have thou prepared me …’ This is the 20th Old Testament prophecy in Hebrews (10:5-9; Ps. 40:6-8). This was fulfilled during the first advent of Christ. Obedience is the great lesson here. It was not God’s will for animals to be offered to redeem man, but that a human victim of infinite merit should be offered for his redemption. That there might be such a victim, a body was prepared so God could be manifest in flesh and take man’s place (Gen. 3:15; Isa. 7:14; 9:6-7; Matt. 1:18-23; Rom. 8:3-4; Heb. 2:9-18; 10:5-9). Christ came to be just such a sacrifice (10:5-9; Ps. 40:8).

‘Prepared me’ – this refers to being perfect (2Cor. 13:11) The Greek word katartizo means to adjust; put in order again; restore; repair; and settle by mediation. Translated “mend” (Matt. 4:21; Mark 1:19); “restore” (Gal. 6:1); fit (Rom. 9:22); “prepare” (Heb. 10:1-39); “frame” (Heb. 9:3); “perfectly joined together” (1Cor. 1:10); “be and make perfect” (Matt. 21:16; Luke 6:40; 1Thess. 3:10; 2Cor. 13:11; Heb. 13:21; 1Pet. 5:10).