Deuteronomy 26-28…Offerings, the altar at Mount Ebal, and blessings/curses for obedience/disobedience.
There are a number of Old Testament passages that figure prominently in the New Testament. In Galatians 3:10–14, several of them are quoted by Paul, and he uses these Old Testament passages as proof texts for the doctrine that sinners are justified through faith alone. Those who trust in Jesus Christ to save them from their sins understand that it was Jesus’ suffering upon the cross that turned aside God’s wrath and anger. But this was not yet clear in the Old Testament when these passages first appeared.
A key text quoted by Paul in Galatians is Deuteronomy 27:26. Moses writes, “Cursed be anyone who does not confirm the words of this law by doing them.” This passage makes it plain that God is not going to grade the final exam for eternal life on a curve. In order to avoid God’s curse, God demands that we obey His law perfectly. Those who fail to do so come under the wrath of God. That this is what Moses meant becomes clear in Matthew’s gospel, where a rich young man claimed to have obeyed all the commandments. When Jesus exposed him as a law-breaker and therefore subject to the curse, the young man went away with great sorrow. Witnessing this exchange, Jesus’ disciples asked Him, “Who then can be saved?”. Jesus reminded them that people do not obey God’s law; they cannot save themselves — it is impossible. But all things are possible for God.
This is why the Bible needs to be understood as systematic and interconnected. The Old Testament is rich with clues, riddles, and pictures, all pointing to Christ. We must interpret these Old Testament texts in light of the New Testament, and vice versa. Deuteronomy 26-28 clearly shows that we need a Savior, because we cannot fulfill the law. Thankfully Christ did perfectly, and His life can be counted as ours if we repent and believe in Him.