In Romans 4:13, Paul states that Abraham "received the promise that he would be heir of the world." But I can't find a direct promise to Abraham of such a thing. He is promised a great deal of descendants, the land of Canaan, and that the nations would be blessed by him, but seemingly nothing that says he would inherit the world. What did Paul mean by this and where did he get the idea?
So write Sanday and Headlam (A critical and exegetical commentary on the Epistle to the Romans, 5th edn (ICC; T & T Clark, 1902), p. 111). They don't go on to explain much, and here James Denney (notable Scottish theologian) does a better job in the Expositor's Greek Testament (Hodder & Stoughton, 1897) vol. 2, p. 618. Yes, those are old commentaries, but not a lot has changed on this front in the century or so since, and similar statements get repeated in more recent work (e.g., Douglas Moo's 1996 NICNT commentary).
Denney takes note of some later rabbinic tradition that understood the promise to Abraham in a much extended sense. But there is evidence that this notion was current in the pre-Christian era and, in all likelihood, would have been known to Paul (or at least could have been). I have in mind in particular the book of Jubilees,1 where the Lord renews to Jacob the promises made earlier to Abraham (Jubilees 32:19, elaborating Genesis 35:12):
Even if there was a precedent for this sort of language (and this seems to me the most straightforward explanation for Paul's use of it here), there remains the question of what he meant by it. There is, minimally, the notion shared with Paul's Jewish context -- that the Abrahamic inheritance was "cosmic" rather than local. Beyond that, there is the use of kosmos elsewhere in Romans, and in 5:12-13, and 11:12 and 15, where the overcoming of sin in the world is tied up with the work of the messiah and Jewish/Gentile inclusion. In some measure, this is anticipated in the "inheritance" of 4:13.
There is a more distant echo, perhaps, in 1 Corinthians 3:21-23, where Paul is concluding his argument to the Corinthian church not to be partisan:
If, in Paul's conception, Jesus represents the one in whom the promise to Abraham is ultimately fulfilled (Romans 4:24-25), then the connection between these texts is quite strong.2
In your haste you may have skipped over perhaps the most important aspect of God's promise to Abraham while he was still living with his father's family in Ur.
About 25 years later, God appeared again to Abram and renamed him Abraham, renewing the promise He made to Abraham a quarter-century previously. Abram, of course, means exalted father. Abraham means father of a multitude of nations. Now that is the world of which Abraham was the heir.
Why was he the heir of the world? Because he inherited the promise of God, when he
We do not often do it, but put those promises to Abraham side by side with three great verses from Ephesians 2:
Abraham became a true believer in God in the same way we today become true believers in Jesus Christ. The starting point is God's grace. Abraham was no more deserving of God's grace than any other person, since he too was a child of Adam and hence a sinner. Nevertheless, God chose him to help fulfill His plan for the ages by calling Abraham out of paganism and into the worship of the one true God--YHWH, God Most High (El Elyon), the LORD God Most High, possessor of heaven and earth, and Lord God (Adonai-Lord/Master). See Genesis 12:1; 14:18 and 22; and 15:2.
God's gift of grace to Abram was free, as was the gift of believing faith. All Abram did was to decide to exercise that faith, which he did. God then honored that decision and accounted it to Abram as righteousness. So it is today, we
We get a deeper appreciation of the magnitude of Abraham's decision to obey God, by his having
Abraham is heir of the world, because in God's Sovereignty he was chosen to be the exemplar of faith, bar none, for hundreds of generations of believers in God, a veritable world of heirs of faith, peopled by those who, like Abraham, believe in God, and to whom God graciously imparts His righteousness.
Moreover, Abraham will remain the heir of the world until God, in Christ, finishes building His church, despite the attempts of the devil and his minions to sabotage His work, and calls His church to heaven to be united with her bridegroom. Then together, they will celebrate the Marriage Supper of the Lamb, and will share in His glory for ever and ever. As the hymn writer put it:
The answer lies in the understanding of the word "Kosmos", which in English is translated "world", yet has a variety of meanings in the Greek. I am not a linguist, but after searching, found this exposition by A.W. Pink:
After listing 6 other meanings of the word "Kosmos", he arrives at this one, which is famous, I suppose, because it includes John 3:16:
In conclusion, since the word "Kosmos" is used in the verse you quote (viz., Romans 4:13), it does not translate to "earth" but to "realm". Moreover, judging from the context in Romans 4, the "heir of the world" is the "heir by faith, not by the law". Since inanimate 'earth' cannot have 'faith', the world (Kosmos) can rightly be translated "believers", since Abraham is the Father by faith of all those--both Old- and New Testament saints--who believe God.
A further exposition of A.W. Pink's pamplet can be found here.
According to the plain and normal reading of the Bible, "the world" would be blessed through Abraham (Gen 18:18 and Acts 3:25 with Gal 3:8). The nuance is that the lesser is blessed by the greater (Heb 7:7). If the nations are blessed through Abraham, the connotation is that Abraham is greater than the nations. His seed, who represents all the promises given to Abraham (Gal 3:16), therefore inherits the nations as the "Anointed" (Ps 2:8), who will rule the nations "with a rod of iron and shatter them like pottery." This "Anointed" seed is the "Melchizidek" who is greater than Abraham, which brings us back to Hebrews 7:7. In summary, this promised seed inherits the promises, since he is greater than Abraham (and greater than King David according to Matt 22:41-45 compared with Ps 110:1-4, which references the son of David as the priest according to order of Melchizidek).