15 God also said to Abraham, “As for Sarai your wife, you are no longer to call her Sarai; her name will be Sarah. 16 I will bless her and will surely give you a son by her. I will bless her so that she will be the mother of nations; kings of peoples will come from her.”17 Abraham fell facedown; he laughed and said to himself, “Will a son be born to a man a hundred years old? Will Sarah bear a child at the age of ninety?” 18 And Abraham said to God, “If only Ishmael might live under your blessing!”19 Then God said, “Yes, but your wife Sarah will bear you a son, and you will call him Isaac. I will establish my covenant with him as an everlasting covenant for his descendants after him. 20 And as for Ishmael, I have heard you: I will surely bless him; I will make him fruitful and will greatly increase his numbers. He will be the father of twelve rulers, and I will make him into a great nation. 21 But my covenant I will establish with Isaac, whom Sarah will bear to you by this time next year.” 22 When he had finished speaking with Abraham, God went up from him.23 On that very day Abraham took his son Ishmael and all those born in his household or bought with his money, every male in his household, and circumcised them, as God told him. 24 Abraham was ninety-nine years old when he was circumcised, 25 and his son Ishmael was thirteen; 26 Abraham and his son Ishmael were both circumcised on that very day. 27 And every male in Abraham’s household, including those born in his household or bought from a foreigner, was circumcised with him.REFLECTIONSWritten by Stephen SheadThe tests of faith keep coming thick and fast for Abraham. You might remember that Abraham had fathered Ishmael through Sarah’s servant Hagar. That whole saga had been ugly and messy – but for the next 13 years, God hadn’t said anything about it. Abraham would have assumed Ishmael was the son through whom God would fulfil his promise of many descendants – after all, the promise so far had only talked about Abraham, not Sarah.Now, 13 years later, when Sarah is well past the natural physical ability to bear children, God drops the bombshell: “No – Sarah will have a son, and he will be the child of the promise.”Abraham might have laughed for a moment (I would have been incredulous for a lot longer). But his obedience to God shows what Paul says in Romans 4 – he believed this impossible promise as well, because he knew that God is “the God who gives life to the dead and calls into being things that were not” (Rom. 4:17).God has not changed – and it’s so much easier for us to believe God’s promise of eternal life to those who trust in Jesus, because he raised Christ from the dead to glorious life.ABOUT THE AUTHORStephen is our Senior Minister and leads our Bossley Park Congregation