In spite of their sins and lack of faith, God was still faithful to the promise He made to Abraham and Sarah. He came to them in the midst of their brokenness and promised them a son of love. The scene in Genesis 18 is full of comedic irony, as when Sarah heard God promise that a child will come to Abraham by her, and, listening outside, began to laugh. She literally laughed at the promise of God and then denied her laughter when God called her on it. Her lack of faith was quickly masked with deceit and evasiveness. It was at this moment that God told them to name their yet-unconceived child “Isaac.” Many take God’s decision to name the boy Isaac as a sign of God’s judgment or chiding; they laughed, so God makes them name the child Isaac (which means “laughter”) as a means of forever reminding them that they laughed at the promise of God.
While that is plausible, something far more beautiful and redemptive was likely at work. The name Isaac is found in the Old Testament often associated with God Himself laughing at His enemies (Pss. 2:4; 37:13; 59:8). The ultimate enemy at which God laughs is death. In fact, it is death that most clearly threatens the covenant promise. When Abraham finally conceives the son of the covenant promise, he is not simply referred to as being old, but as being “as good as dead” (Rom. 4:19; Heb. 11:12). This is the real point of Hebrews 11:11–12. God brought Abraham and Sarah to the point of death before giving them the son of his promise. Isaac and Sarah were both as good as dead, and yet God, the resurrecting God that He is, gave life in the place of death. Upon this stage of death, God not only set Isaac, one born from the dead, but God also dramatically displayed His power over death itself. From Abraham would come as many children as the sand on the seashore (Heb. 11:12). God triumphs over death and barrenness.
Of course, Abraham, Sarah, and Isaac eventually succumbed to death. Even though God prolonged the physical abilities of their bodies, those bodies eventually expired. Something, or someone, must triumph over death and its cause (sin) in order for God’s people to know the true triumph of God. The covenant promise was not simply longer life but eternal life, and that life comes only through the Son who is greater than Isaac—Jesus. It’s not surprising that the Son of God who looks death in the eyes and laughs at it was born in a similarly miraculous manner. When Jesus, Abraham’s greatest son, was born, He came in the context of the supernatural work of God. He was not born of an old woman but a young virgin. But is that any less “inconceivable”? That a virgin should conceive—who could imagine? But such was the plan of God that death should be triumphed over—even laughed at—when Jesus, the greater son of Abraham and righteous Son of God, entered the world.
Is anything impossible with God? Often, Christians face the impossible. But just as Abraham and Sarah were refined by their God-designed infertility, so also are we refined by the various contexts in which God displays His strength through our weakness. With God, nothing is impossible; nothing is truly “inconceivable.”