In sacrifice and offering you have not delighted, but you have given me an open ear. Burnt offering and sin offering you have not required. Then I said, “Behold, I have come; in the scroll of the book it is written of me: I delight to do your will, O my God; your law is within my heart.” I have told the glad news of deliverance in the great congregation; behold, I have not restrained my lips, as you know, O Lord. I have not hidden your deliverance within my heart; I have spoken of your faithfulness and your salvation. I have not concealed your steadfast love and your faithfulness from the great congregation.
God set up a system of sacrifices and offerings for His Old Testament people, Israel, in order to atone for, or cover over, their sin. These sacrifices and offerings paid the price for sin, which is death (Romans 6:23), and thereby averted the wrath and judgment of God. However, we know from the book of Hebrews that these Old Testament sacrifices were ultimately insufficient to pay the full price for people’s sin against God. “For it is impossible for the blood of bulls and goats to take away sins” (Hebrews 10:4).
Knowing this Old Testament background helps us see the beauty of today’s passage. Psalm 40 talks about one who delights to do the will of God, someone with the law of God written on their heart. This is a description of the One who came to be a perfect sacrifice, a perfect offering for our sin. And we know from the rest of Scripture that only Jesus Christ fits this description.
Christ’s delight was to do the will of God perfectly, and He in fact did God’s will without sinning (Hebrews 4:15). The law of God was written on His heart and He obeyed the Father completely during His earthly ministry. Therefore, Christ alone could be a sacrifice for sinners by offering His life on the cross to pay the price for our sin.
The author of Hebrews cites today’s passage in order to show that Christ’s sacrifice is superior to all the sacrifices and offerings that came before (Hebrews 10:5–14). Those sacrifices had to be offered repeatedly, but not so with the sinless Son of God. He was, as Hebrews 10:14 tells us, a sufficient sacrifice: “For by a single offering he has perfected for all time those who are being sanctified” (Hebrews 10:14).