Romans 4:17-19

That’s what the Scripture means when it says: “I have made you the father of many nations.” He is our example and father, for in God’s presence he believed that God can raise the dead and call into being things that don’t even exist yet. Against all odds, when it looked hopeless, Abraham believed the promise and expected God to fulfill it. He took God at his word, and as a result he became the father of many nations. God’s declaration over him came to pass: “Your descendants will be so many that they will be impossible to count!” In spite of being nearly one hundred years old when the promise of having a son was made, his faith was so strong that it could not be undermined by the fact that he and Sarah were incapable of conceiving a child.