The answer to this question is not as opaque as it may seem. In fact, we need look no further than God’s promise to Abraham in Genesis 12 to find the answer to the curse of sin as well as the hope for the future of all peoples and nations.
From the beginning to the end of the Old Testament we read that the scope of God’s rule is universal (Genesis 1:1; Isaiah 54:5; Jeremiah 32:27). He is the only true, eternal, and living God, and all nations are invited to worship him (Psalm 117:1), not just Israelites. His concern is for anyone who bears his image (Genesis 1:26–28), even though all stand guilty before him as a result of Adam’s sin (Genesis 3).
God’s concern for all nations comes into greater focus in Genesis 12. After a crescendo of worldwide evil outlined in Genesis 1–11, God calls a man named Abraham and makes the following promises:
Go from your country and your kindred and your father’s house to the land that I will show you. And I will make of you a great nation, and I will bless you and make your name great, so that you will be a blessing. I will bless those who bless you, and him who dishonors you I will curse, and in you all the families of the earth shall be blessed. (Genesis 12:1–3)
Through Abraham’s story comes God’s solution to the entire world’s sin problem. Either blessings or curses will come to all people groups through their relation to Abraham. It is clear, then, that God’s blessing is not only for those who are physical descendants of Abraham (i.e., the Israelites). In keeping with God’s promise in Genesis 3:15, Abraham’s blessing is the antidote to the curse of the world.
But how does Abraham bless the whole world within the Old Testament? Isn’t this part of Scripture entirely focused on one nation, Israel?
The solution is hinted at in Genesis 17: Abraham’s blessing includes the promise that he would sire kings (17:6; see also Genesis 35:11). Through a king from Abraham’s offspring, God’s rule would extend beyond Israel’s borders to the ends of the world. This is consistent with the blessing that Jacob pronounces over Abraham’s great-great-grandson, Judah: “The scepter shall not depart from Judah, nor the ruler’s staff from between his feet, until tribute comes to him; and to him shall be the obedience of the peoples” (Genesis 49:10). Later, Balaam’s oracles make a similar connection between Abraham’s offspring and kingship: “A star shall come out of Jacob, and a scepter shall rise out of Israel.… And one from Jacob shall exercise dominion and destroy the survivors of cities!” (Number 24:17, 19).
With this connection in mind, we can infer that by the time the Israelites enter Canaan, the Old Testament expectation is that the fulfillment of the promised blessing to Abraham would be realized through a triumphant king of Israel, a descendant from Judah, who would defeat Israel’s enemies, and, somehow, disseminate God’s blessing to the world, reversing the curse.
But this raises a question: who is the kingly offspring of Abraham?
Abraham’s blessing continues through Isaac, Jacob, and Judah, and then eventually we read of God’s promise of an eternal throne to the offspring of David (2 Samuel 7:12–13). Since David is an offspring of Abraham from Judah’s line, we can say confidently that the blessing of Abraham will come through King David’s line. But this blessing extends beyond Israel.
Psalm 72:17 says of David’s kingly heir, “May his name endure forever, his fame continue as long as the sun! May people be blessed in him, all nations call him blessed!” This king in David’s line will not only reign forever but he will also be the mediator of blessing to the entire world! The focus, then, is no longer solely on the national offspring of Abraham who will collectively bless the whole world but on one particular offspring who is able to inherit an eternal throne.
Do the prophets foretell a coming king in David’s family who will bless the nations?
Indeed they do. To take one example, the prophet Isaiah speaks of a Spirit-empowered Messiah/King from David’s line (11:2; 61:1) who would bless God’s people and pour out his Spirit on them (Isaiah 44:3). The result would be a people who were a witness to the nations: “Their offspring shall be known among the nations, and their descendants in the midst of the peoples; all who see them shall acknowledge them, that they are an offspring the Lord has blessed” (Isaiah 61:9).
Isaiah was looking to the future, for the “offspring” that would be a witness to the nations and blessed by the Lord relates not only to physical Israel but to spiritual Israel as well (see Romans 9–11). Jews and Gentiles who trust in the Messiah will be united as a seamless whole, each bearing the mark of the “name” of David’s greater Son. Both are called “blessed.”
Putting it All Together
Putting together everything we’ve seen, we can now arrive at a theological synthesis, namely, that the blessing of Abraham goes from Abraham, through the Davidic Messiah, to the nations.
From creation to new creation, God’s plan has always been to spread the knowledge of his glory over the dry land as the waters cover the sea (Isaiah 11:9; Habakkuk 2:14). This grand program centers on the redemption he offers through his Messiah, the seed of the woman (Gen 3:15), David’s greater Son (Psalm 110), the one who comes “to the house of Israel” (Matt 15:24), but whose name, Jesus, the New Testament later says is to be proclaimed “to all nations” (Luke 24:47). Indeed, the apostle Paul writes that Christ redeemed us from the curse of the law “so that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we might receive the promised Spirit through faith” (Galatians 3:14).
Is God concerned for the nations in the Old Testament? The answer is a resounding yes!
 Notice also that Abraham’s story is not simply about one man and his family but is set within the context of world history (see the “Table of Nations” in Genesis 10).
 Notice the similarities between Numbers 24:17, 19 and Genesis 49:10.
 Psalm 72:17 is an echo of God’s promise to Abraham in Genesis 12. The words “May his name endure forever” recall the words of Genesis 12:2: “I will make your name great.” Likewise, the words “May… all nations be blessed in him” in Psalm 72 recall God’s promise in Genesis 12:3: “in you [Abraham] all the families of the earth shall be blessed.”