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.

For if they of the Law are heirs, faith is made void and the promise is made of no effect;

Therefore it is of faith so that it might be according to grace; for the promise to be made sure to all the seed, not only to that which is of the Law, but to that also which is of the faith of Abraham, who is the father of us all

He did not stagger at the promise of God through unbelief, but was strong in faith, giving glory to God,

That is, not the children of the flesh are children of God; but the children of the promise are counted for a seed.

For this is the word of promise: "At this time I will come and Sarah shall have a son."