Romans 4:13
Romans 4:1313For the promise to Abraham and his offspring that he would be heir of the world was not given through the law, but through the righteousness that comes by faith.
Watchtower commentary takes as describing the promise to Abraham as inheritance of "a world" — read as the future restored earth populated by faithful Witnesses. The "righteousness by faith" is Abraham's friendship status with Jehovah, and his "offspring" inheriting the world fits the Watchtower's earthly-paradise hope for the great crowd. The promise to Abraham is essentially material and geographic.
The promise to Abraham was that he would be "heir of the world" — kosmou, the entire creation, not merely the land of Canaan. And Paul's argument is that this universal inheritance comes "through righteousness by faith," not through law-keeping. Pair this with : "if you belong to Christ, then you are Abraham's seed and heirs according to the promise." Every believer in Christ inherits with Abraham — heir of the cosmos, not heir of Watchtower Heights. The Watchtower's two-class earthly hope splits the inheritance Paul makes singular and universal. Abraham's heirs do not divide into a heavenly anointed and an earthly great crowd; they are one people, one promise, one world to inherit through Christ.
The NWT renders the Greek genitive klēronomon kosmou as "heir of a world" — consensus reads "heir of the world" (ESV/NASB/NIV) or "heir of the world" (KJV). The Greek lacks the article, but the consensus translation tradition treats the genitive as definite (a known, singular world). The NWT's indefinite "a world" subtly accommodates the JW two-realm cosmology — Abraham inherits some earthly realm rather than universal Lordship in Christ.