For the promise to Abraham or to his seed, for him to be heir of the world, was not through law, but through a righteousness of faith.

For if those from law are heirs, faith has been made void, and the promise has been made useless.

Because of this it is from faith, so that it is according to grace, in order for the promise to be sure to all the seed, not only to the seed from the law, but also to the seed from the faith of Abraham, who is father of us all

And he did not waver in unbelief at the promise of God, but became strong in faith, giving glory to God,

That is, the children of the flesh, these are not children of God, instead, the children of the promise are reckoned for seed.

For this is the word of promise: At this time I will come, and there will be a son by Sarah.