Shared ground
Paul’s main point is clear in the flow of Romans 4:13–17: the promise God gave to Abraham and his “seed” is not delivered through keeping law, but through “the righteousness of faith.” (Explicit textual claim.) Paul argues that if inheritance is tied to law-identity, then faith is emptied and the promise becomes ineffective (vv.14–15). He also links law to “wrath,” meaning law highlights wrongdoing and brings accountable consequence (v.15). Therefore the promise rests on faith so it can be a gift (“according to grace”) and so it can be secure for a wider family, not limited to those connected to the law (v.16). Paul grounds the “many nations” family claim in Scripture (v.17).
Where interpretation differs
1) What “heir of the world” means (v.13). Some read it as a broad, ultimate inheritance that reaches the whole world (for example, the worldwide scope of blessing and a renewed creation). Others read it more narrowly as shorthand for the land-and-nations promise to Abraham, now expanded beyond one territory, but still mainly about belonging to the promised people rather than a literal “world-ownership.”
2) Who “seed” refers to in this argument (vv.13, 16). Many see “seed” as Abraham’s family redefined around faith—those who share Abraham’s trust, including non-Jews (v.16). Others emphasize that “seed” can also mean Abraham’s physical descendants, and that Paul’s point is about how both physical descendants and non-descendants become heirs: not by law-keeping, but by faith.
3) What “where there is no law, there is no disobedience” means (v.15). Some take “law” here mainly as the Mosaic law, so Paul is speaking about accountability in relation to that covenant. Others take it more broadly: when there is no stated command, there is no chargeable violation of that command, even though wrongdoing may still exist in other senses.
Why the disagreement exists
Paul uses compressed phrases (“heir of the world,” “seed,” “those of the law,” “no law”) without pausing to define each term. He is also working within Abraham’s story while addressing a mixed community’s question of identity markers, so readers debate whether each phrase is primarily about land/worldwide inheritance, about covenant membership, or both.
What this passage clearly contributes
This section contributes a tight logic: promise-through-law would undercut faith and destabilize the promise (vv.14–15); promise-through-faith fits “grace” (gift) and therefore can be “sure” for “all the seed” (v.16). It also clearly ties the enlarged family (“many nations”) to Scripture and to the kind of God Abraham trusted—one who can give life to the dead and speak about what does not yet exist as though it does (v.17; see Romans 4:17).