Exodus 24 contains another one of those cryptic Old Testament passages that is illuminated by the New Testament.
"Moses took half of the blood and put it in basins, and half of the blood he dashed against the altar. Then he took the book of the covenant, and read it in the hearing of the people; and they said, 'All that the Lord has spoken we will do, and we will be obedient.' Moses took the blood and dashed it on the people, and said, 'See the blood of the covenant that the Lord has made with you in accordance with all these words'" (vs. 6-8).
What is Moses doing? Why make such a bloody mess of things - literally? What does it mean for the altar to be dashed with half of the blood of the sacrifices and the people to be dashed with the other half?
The Book of Hebrews gives us some answers. "Hence not even the first covenant was inaugurated without blood. For when every commandment had been told to all the people by Moses in accordance with the law, he took the blood of calves and goats, with water and scarlet wool and hyssop, and sprinkled both the scroll itself and all the people. saying, 'This is the blood of the covenant that God has ordained for you.' And in the same way he sprinkled with the blood both the tent and all the vessels used in worship. Indeed, under the law almost everything is purified with blood, and without the shedding of blood there is no forgiveness of sins" (Hebrews 9:18-22).
Both Testaments are teaching the same thing: the forgiveness of sin is costly. It requires blood. But what was prefigured in the Old Testament by way of sacrificing bulls and goats comes to its ultimate fulfillment in the cross of Christ at Calvary. We are saved through the sprinkling of His blood upon us.
This is just one of many examples of the foreshadowing we can find in the Old Testament of what is leading toward God's great act of salvation.