Genesis 20-21

What’s Happening?

Genesis has been building a promise since Eden. God swore that one day a child of the woman would crush the serpent, undoing the curse of death and bringing life back to the world (Genesis 3:15). Every generation since has left us wondering: will this child really come? Will God keep his promise?

God chose Abraham to carry this hope. Through his family, blessing would come to the nations, life would spring up in a dying world, and a people would inherit a land of flourishing. But Abraham’s story so far has been full of failure, compromise, and delay. In Genesis 20–21, the promise looks as fragile as ever.

Abraham, fearing for his life, tells Abimelech king of Gerar that Sarah is his sister (20:2). If Sarah becomes part of Abimelech’s household, how will God’s promised child be born? But God intervenes, protecting Sarah and preserving the family line (20:6). The covenant will not collapse because of Abraham’s fear.

Then it happens: Isaac is born (21:2). Against all odds, God gives life where there was none. The seed of promise is carried forward. Yet immediately the story reminds us how vulnerable it all still is. At Isaac’s celebration, Sarah demands that Hagar and Ishmael be cast out (21:10). Banished into the wilderness and nearly dying of thirst, Hagar cries out in despair. But God hears. Because of his covenant with Abraham, God provides for Ishmael too (21:17–18). The promise line is Isaac’s, but God’s mercy and faithfulness spill over beyond the boundaries Abraham and Sarah imagined.

The chapter ends with Abimelech, once a threat, now recognizing that God is with Abraham and seeking peace with him (21:22). God’s promise has survived fear, barrenness, and exile. The seed of blessing is alive.

Where is the Gospel?

This story shows why we need a child of promise. Humanity cannot bring life out of death. We cannot crush the serpent’s head. Abraham’s fear nearly destroyed the covenant. Sarah’s jealousy nearly ended a family. The promise could not rest on human strength. It needed God to act.

That’s what Jesus is: the true child of promise. Born not by human effort but by God’s Spirit, he carries the covenant forward to its fulfillment. Where Adam and Eve grasped at life apart from God, Jesus is life itself. Where Cain spilled his brother’s blood, Jesus sheds his own to bring flourishing out of death. Where Abraham and Sarah faltered, Jesus stands faithful.

And here’s the good news for us: in Jesus we are reborn as new creations. By faith we become children of the promise, grafted into Abraham’s family (Galatians 3:29). God’s Spirit marks us as his own, just as Isaac’s birth marked the covenant’s survival. We are not children of fear or slavery, but of promise and freedom. And as God blessed Abraham’s family to bless the nations, so Jesus sends us into the world to bring life and flourishing where death once reigned.

See for Yourself

I pray that the Holy Spirit would open your eyes to see the God who keeps his promises even when we fail. And may you see Jesus as the true child of promise, who makes you part of his family so that God’s blessing and life might cover the earth.