I believe whenever the word "seed" is used it is posterity. Only Jews are posterity of Abraham's natural seed. Believing Gentiles are of the faith of Abraham, but not his seed or posterity.
Please explain your view of these scriptures. I'm not quoting all the verses but surely do expect you to address these in the context of the whole teaching but please be clear as to which verses in the whole teaching uphold your understanding or if any of them do.
Romans 4 KJV
1 What shall we say then that Abraham our father, as pertaining to the flesh, hath found?
2 For if Abraham were justified by works, he hath whereof to glory; but not before God.
3 For what saith the scripture? Abraham believed God, and it was counted unto him for righteousness.
9 Cometh this blessedness then upon the circumcision only, or upon the uncircumcision also? for we say that faith was reckoned to Abraham for righteousness.
10
How was it then reckoned? when he was in circumcision, or in uncircumcision?
Not in circumcision, but in uncircumcision.
11 And he received the sign of circumcision, a seal of the righteousness of the faith which he had yet being uncircumcised: that he might be the father of all them that believe, though they be not circumcised; that righteousness might be imputed unto them also:
12 And the father of circumcision to them who are not of the circumcision only, but who also walk in the steps of that faith of our father Abraham, which he had being yet uncircumcised.
13 For the promise, that he should be the heir of the world, was not to Abraham, or to his seed, through the law, but through the righteousness of faith.
14 For if they which are of the law be heirs, faith is made void, and the promise made of none effect:
16 Therefore it is of faith, that it might be by grace;
to the end the promise might be sure to all the seed;
not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all,
17 (As it is written, I have made thee a father of many nations,) before him whom he believed, even God, who quickeneth the dead, and calleth those things which be not as though they were.
18 Who against hope believed in hope,
that he might become the father of many nations, according to that which was spoken, So shall thy seed be.
Also could you give scripture that says that the Israelites were promised the "whole world" as their inheritance? Thank you.