Sarah is in her nineties and I will soon be 100. Then Abraham tried to talk some common sense into God. Look, we have the boy, Ishmael. Let him be my heir. Sarah will give birth to this child next year.
Some strangers come to visit.
It turns out they are special messengers from God, and when they tell Abraham that next spring he and Sarah will have a son, Sarah overhears what they are saying, and she, too, laughs at the promise of God. At long last, in chapter 21, the promise made way back in chapter 12 is fulfilled. Well, the promise is fulfilled if you think having one son is fulfilling the promise of having more descendants than you can count. Abraham and Sarah trusted God to the point that having only one child, Isaac, was for them, by faith, the fulfillment of the promise. Now, let's try to identify some of what the Abraham-Sarah stories tell us about faith and the struggle to live faithful lives.