For the promise made to Abraham and his descendants that the world should belong to him did not come to him or his descendants through the Law, but through the uprightness that resulted from his faith.

For if it is the adherents of the Law who are to possess it, faith is nullified and the promise amounts to nothing!

That is why it all turns upon faith; it is to make it a matter of God's favor, so that the promise may hold good for all Abraham's descendants, not only those who are adherents of the Law, but also those who share the faith of Abraham. For he is the father of all of us;

as the Scripture says, "I have made you the father of many nations." The promise is guaranteed in the very sight of God in whom he had faith, who can bring the dead to life and call into being what does not exist.

He did not incredulously question God's promise, but his faith gave him power and he praised God

That is to say, it is not his physical descendants who are children of God, but his descendants born in fulfilment of the promise who are considered his true posterity.

For this is what the promise said: "When I come back at this time next year, Sarah will have a son."