
Paul says Abraham was promised his offspring would become “heirs of the world,” although Genesis defines the land promise narrowly. But by the first century, there were several Second Temple texts that expanded that land promise to include the whole world (Sirach 44:21; Jub. 32:19; 1 Enoch 5:7, 4 Ezra 6:55-59). Jesus says “the meek will inherit the earth” (Matt 5:5), very similar to 1 Enoch 5:7.
Sirach 44:21 (NRSV) Therefore the Lord assured him with an oath that the nations would be blessed through his offspring; that he would make him as numerous as the dust of the earth, and exalt his offspring like the stars, and give them an inheritance from sea to sea and from the Euphrates to the ends of the earth.
1 Enoch 5:7 But to the elect there shall be light, joy, and peace, and they shall inherit the earth. To you, wicked ones, on the contrary, there will be a curse.
Jubilees 32:19 And I shall give to your seed all of the land under heaven and they will rule in all nations as they have desired. And after this all of the earth will be gathered together and they will inherit it forever.”
All of these texts are based on the Hebrew Bible Isaiah 2, for example, describes Zion as the exalted mountain to which all the nations will stream. From Zion the Lord himself will reign and the nations will come to Zion to “learn the ways of the Lord.” In Daniel 7:14 the Ancient of Days gives a “son of man” authority to rule over all of the nations in an “everlasting dominion that will never end.” Even a text like Psalm 2 indicates the Lord’s anointed king could potentially receive the nations as an inheritance.
Paul certainly looks forward to a future kingdom (1 Cor 15:20-28, Phil 2:5-11), but in this text the descendants of Abraham are those who are being justified by faith in Jesus. Paul has a Jewish, apocalyptic view of what God will do in the future. But here in Romans 4 he connects the “offspring of Abraham” with those who have faith in Jesus, the “in Christ” people. The nations are the Gentiles who are being justified by faith and not works of the Law.
Imagine how this would sound to Roman Christians who were used to hearing that Rome controlled the world (Jewett, Romans, 325). It is unimaginable that an extremely small group of followers of Jesus would somehow challenge the Roman Empire. From the perspective of the mid-first century, Christianity had no impact on the culture of the Empire. But it was not long at all before Christianity began to challenge the thinking of the Roman world.
The three repetitions of the covenant are important since the progressively narrow the promised child from Abraham’s heir (Gen 12) to an heir coming from his own body (Gen 15) and then specifically Sarah’s child (Gen 17). At first, Abraham’s heir was an adopted child, Eliezer of Damascus, or perhaps Lot. After the second announcement, Abraham and Hagar have a child, Ishmael. After the third God specifically says the promised heir will be from Sarah and adds circumcision on the eighth day. Ishmael is circumcised (Gen 17:23), but he is thirteen at the time (Gen 16:16, Abraham is 86 when he is born, and Gen 17:1, he is 99 when the covenant is repeated a third time).
There does seem to be some evidence some streams of Second Temple Judaism considered Abraham’s faith so or faithful acts as something to boast in. For example, Sirach 44:19-22 claims Abraham “perfectly kept the Law.” In the Testament of Abraham, a young Abram rejects his father’s idols and mocks them as useless. In response to this, God gives the young Abram the promise of Genesis 12. In the Mishnah, Genesis 26:5 is interpreted as an indication Abraham kept the entire Torah before it was even given!
Paul’s main point in Romans 4 is simple. In Genesis 15:6 God declared Abraham righteous, before he was given the sign of the covenant (Gen 17) and long before the Law was given. For Paul, Gentiles are declared righteous just as Abraham was, by faith.