What Does Genesis 17:15-22 Mean?
The law in Genesis 17:15-22 defines God's promise to Abraham and Sarah, renaming Sarai as Sarah and declaring she will bear a son, Isaac, through whom the covenant will continue. Though both Abraham and Sarah are advanced in age - Abraham nearly 100 and Sarah 90 - God affirms His power to fulfill His promises in His timing. This passage highlights divine initiative, human doubt, and the establishment of a chosen lineage through which blessing will flow to nations.
Genesis 17:15-22
And God said to Abraham, "As for Sarai your wife, you shall not call her name Sarai, but Sarah shall be her name. I will bless her, and moreover, I will give you a son by her. I will bless her, and she shall become nations; kings of peoples shall come from her.” Then Abraham fell on his face and laughed and said to himself, "Shall a child be born to a man who is a hundred years old? Shall Sarah, who is ninety years old, bear a child?" And Abraham said to God, "Oh that Ishmael might live before you!" God said, “No, but Sarah your wife shall bear you a son, and you shall call his name Isaac. I will establish my covenant with him as an everlasting covenant for his offspring after him. As for Ishmael, I have heard you; behold, I have blessed him and will make him fruitful and multiply him greatly. He shall father twelve princes, and I will make him into a great nation. But I will establish my covenant with Isaac, whom Sarah shall bear to you at this time next year." When he had finished talking with him, God went up from Abraham.
Key Facts
Book
Author
Moses
Genre
Law
Date
Approximately 1440 BC
Key Themes
Key Takeaways
- God fulfills promises in His timing, not ours.
- Faith trusts God even when circumstances seem impossible.
- God's covenant is by promise, not human effort.
God Renames Sarah and Promises Isaac
Building on the covenant God established with Abraham in Genesis 17:1-14, this passage shifts focus to Sarah and the miraculous birth of Isaac.
God renames Sarai as Sarah, signaling her new role as Abraham’s wife and the mother of nations and kings (Genesis 17:15-16). Though Abraham laughs in disbelief at the idea of a child being born to a 100-year-old man and a 90-year-old woman, his reaction shows honest human doubt rather than mockery. Still, God reaffirms His plan: the covenant will pass through Isaac, born to Sarah, not Ishmael, though Ishmael will also be blessed and made the father of twelve princes.
This moment underscores that God’s promises move forward not through human strength but divine power, setting the stage for the next phase of Abraham’s journey of faith.
Abraham's Laughter and the Weight of Divine Promise
This passage dives deep into the tension between human limitation and divine promise, revealing how God reshapes identity, destiny, and faith through seemingly impossible promises.
Abraham's laughter in Genesis 17:17 is more than amusement - it's a natural human reaction to the absurd: a 100-year-old man and 90-year-old woman having a child. Yet in Hebrew, the name 'Isaac' means 'he laughs,' turning Abraham’s doubt into a lasting reminder of God’s power to bring joy where there was none. The renaming of Sarai to Sarah is also significant - while 'Sarai' may mean 'my princess,' 'Sarah' means 'princess of many nations,' showing her role expands far beyond one family. This shift highlights that God is changing names and redefining purpose and legacy.
The covenant’s election of Isaac over Ishmael isn’t about favoritism but divine promise - Isaac is the child of God’s timing and power, not human effort. Though Ishmael is blessed and will father twelve princes (Genesis 17:20), the covenant line runs through Isaac, the child of promise. This distinction teaches that God’s plans often bypass human logic and natural ability, echoing Paul’s later point in Galatians 4:22-23 that the covenant comes through the Spirit, not the flesh.
In the ancient world, inheritance and covenant were often tied to the firstborn, so choosing Isaac was countercultural. Yet God’s choice shows His freedom to work through weakness and surprise, not human systems. This sets a pattern seen later in God calling David the youngest son or Paul saying God chooses the 'foolish' to shame the wise (1 Corinthians 1:27).
God's covenant is not built on what we can do, but on who He is and what He promises to do through us.
This moment of laughter, renaming, and divine selection prepares us for the next step: how Abraham responds in action, not emotion, by obeying God’s command to circumcise his household.
Trusting God's Promises Against All Odds
Abraham's moment of laughter turns into a lasting lesson on what it means to trust God's promises, not our own understanding.
God promised a son through Sarah, not because of their strength or timing, but because of His faithfulness - and this promise ultimately points to Jesus, the true offspring of Abraham through whom all nations are blessed (Galatians 3:16). While the law of circumcision was a sign of the covenant in Abraham’s time, Jesus fulfilled that sign by bringing a new covenant based on faith and the work of the Spirit (Romans 2:29; Colossians 2:11-12).
Faith means trusting God's promise even when it seems impossible to us.
So Christians don’t practice circumcision as a requirement, because Jesus has completed the law and opened the way for all people - Jew and Gentile alike - to be part of God’s family through faith, not physical descent.
Abraham's Faith and the Heart of Justification by Faith
This passage, which includes a name change and a miraculous birth, becomes a cornerstone for understanding how faith, not works, connects us to God’s promises.
The apostle Paul draws directly on this moment in Romans 4:19-21, writing, 'Abraham did not weaken in faith when he considered his own body, which was as good as dead since he was about a hundred years old, or when he considered the barrenness of Sarah’s womb. He did not waver in unbelief but grew strong, giving glory to God, fully convinced that God was able to do what he had promised.' Though Abraham laughed, Paul sees past that moment to the deeper truth: Abraham chose to trust God’s word over his own experience.
Real faith isn’t pretending doubt doesn’t exist - it’s choosing to trust God’s promise even when your circumstances scream otherwise.
Later, in Galatians 4:21-31, Paul contrasts Sarah and Hagar as symbols of two covenants - one based on human effort (Hagar), the other on God’s promise (Sarah) - showing that we, like Isaac, are children of the free woman, born not by natural descent but by the Spirit’s power. This reminds us that our standing with God has always been about faith, not performance, and that truth finds its fullness in Christ.
Application
How This Changes Everything: Real Life Impact
Imagine feeling too old, too broken, or too late for God to do anything new in your life. That’s where many of us are - wondering if our season of purpose has passed. But Abraham and Sarah’s story flips that lie on its head. God didn’t show up when they were strong or young. He showed up when they were past hope. He offered comfort and promised a future so big it made Abraham laugh. That laugh turned into a legacy. When we face impossible situations - infertility, failure, aging, stalled dreams - this passage reminds us that God specializes in the impossible. His timing is not late. It is divine. Our doubt does not disqualify us. It sets the stage for His power.
Personal Reflection
- Where in your life are you letting circumstances override God's promises?
- What 'Ishmael' - a good thing born from human effort - are you holding onto instead of waiting for God's 'Isaac' - His promised best?
- How can you actively trust God's faithfulness this week, even when it doesn’t make sense?
A Challenge For You
This week, write down one promise from God’s Word that feels impossible in your current situation. Every day, read it aloud and thank God that He is faithful, even when you struggle to believe. Share it with a trusted friend and ask them to pray with you.
A Prayer of Response
God, I admit that sometimes I laugh at Your promises because my circumstances feel too heavy. Forgive me for trusting my limits more than Your power. Thank You for being faithful even when I doubt. Help me to trust that You can do what only You can do - in my life, my family, my future. I choose to believe You, like Abraham did.
Related Scriptures & Concepts
Immediate Context
Genesis 17:1-14
God establishes His covenant with Abraham, institutes circumcision, and sets the foundation for the promise of Isaac.
Genesis 17:23-27
Abraham immediately obeys God by circumcising his household, showing faith in action following divine revelation.
Connections Across Scripture
Romans 4:19-21
Paul draws on Abraham’s faith in God’s promise despite his body being 'as good as dead,' echoing Genesis 17.
Galatians 4:21-31
Paul uses Sarah and Hagar as allegories for two covenants, highlighting the child of promise over human effort.
Hebrews 11:11-12
Affirms Sarah’s faith in receiving the promised son, showing that God fulfills His word through faith.
Glossary
places
language
figures
Abraham
The patriarch chosen by God to father a multitude of nations through divine promise, not human ability.
Sarah
Abraham’s wife, renamed by God to signify her role as mother of nations and bearer of the promised son.
Ishmael
Abraham’s son by Hagar, blessed by God but not the child of the covenant promise.