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. 19 And being not weak in faith, he considered not his own body now dead, when he was about an hundred years old, neither yet the deadness of Sara’s womb: 20 He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God; 21 And being fully persuaded that, what he had promised, he was able also to perform. 22 And therefore it was imputed to him for righteousness. Your interpretation of faith and of grace in verse 16 does not make it "sure to all the seed" but only makes it potential because it ultimately depends upon your own participation in obtaining that promise through works. Here Paul begins to define the nature of justification "by faith" as something that makes the promise (justification) "sure to all the seed" (the father of "all that beleive). In order to do this he presents what only God can do or the impossible in verse 17 followed by the illustration of the what neither Abraham or Sarah could help God do as their faculties for assisting God were "dead" inoperable (vv. 18-22). 1. God alone can speak of things not yet as though they are and God alone can raise the dead - He does the impossible without the assistance of creatures. 2. The birth of Isaac was impossible for Abraham and Sarah. The natural facilities were "dead' and therefore it was impossible for them to assist God in accomplishing this promise as they attemtped to assist God in the birth of Ishmael. 3. They hoped AGAINST all hope - meaning there was no POSSIBLE way the promise could be fulfilled apart from God ALONE accomplishing it. Faith that justifies sinners is faith that embraces God and His promises as truth and RESTS in the PROMISE and in the POWER of God ALONE to fulfil his promise WITHOUT PARTICIPATION BY WORKS. And being fully persuaded that, what he had promised, he was able also to perform. Now it was not written for his sake alone, that it was imputed to him; 24 But for us also, to whom it shall be imputed, if we believe on him that raised up Jesus our Lord from the dead; 25 Who was delivered for our offences, and was raised again for our justification. There is no possible way you can ASSIST God in raising Christ from the dead - you can only embrace this truth by faith. There is no possible way you can ASSIST Christ in being delivered for our offences - you can only embrace this truth by faith. There is no possible way you can ASSIST Christ in justifying you as he did it "FOR YOU" and so you can only embrace it by faith. Now, once you have been justified by faith the consequences are obedience out of love for having obtained the promise not in order to obtain the promise.