God's keeps his promises

I am thinking about how it can be possible for God to promise something that seems impossible.
Or to put it another way, how does it work when you believe God has given you faith for something, but you don't see it happening and there is plenty of evidence that it can not and will not happen? What if you have faith for something that seems impossible? I've thought a lot about faith and exercising faith, as well as Jesus words to pray, "thy will be done on earth as it is in heaven." I have also thought a lot about Abraham and his faith walk. God called this childless older man, "the father of many nations". Paul says that God can say such things or make such impossible claims on people because he, "calls into being that which does not exist". God's word is settled in heaven and we are just being brought into alignment with it. Another translation has Romans 4:17 as "calls things that are not as though they were".

About Romans 4:17, Commentator Albert Barnes says, "I regard it as having reference to the strong natural improbability of the fulfillment of the prophecy when it was given, arising from the age of Abraham and Sarah, Romans 4:19. Abraham exercise power in the God who gives life, and who gives it as he pleases. It is one of his prerogatives to give life to the dead (\~nekrouv\~) to raise up those who are in their graves; and a power similar to that, or strongly reminding of that, was manifested in fulfilling the promise to Abraham. The giving of the promise, and its fulfillment, were such as strongly to remind us that God has power to give life to the dead.
And calleth, etc. That is, those things which he foretells and promises are so certain, that he may speak of them as already in existence. Thus is relation to Abraham, God, instead of simply promising that he would make him the father of many nations, speaks of it as already done, "I have made thee," etc. In his own mind, or purpose, he had so constituted him, and it was so certain that it would take place, that he might speak of it as already done."