Genesis 20:1-21:34

Key Verse: 21:1


“Now the Lord was gracious to Sarah as he had said, and the Lord did for Sarah what he had promised.”

Today, God reveals his sovereign plan for Abraham by keeping his promise. The birth of Isaac signals that God is faithful and mighty in his promise. Abraham enters into another spiritual milestone by sending away Ishmael. Let’s believe that God will give us the best when we give up good things we love. I pray that we may learn from Abraham’s bold decision of faith to get rid of Ishmael through this passage. May God bless us to trust God’s promise to the end so that we all may experience his grace and power in our personal pilgrim’s life on the earth.



Look at verses 1-2a. “Now Abraham moved on from there into the region of the Negev and lived between Kadesh and Shur. For a while he stayed in Gerar. And there Abraham said of his wife Sarah, ‘She is my sister.’” Here Abraham goes again. He lied to protect his own life because he thought that there was no fear of God in the new place he moved. His wife-dependency syndrome was resurrected. In chapter 12, Abraham had tried the same lie in Egypt though he was humiliated by Pharaoh and almost lost his wife. He reverted to his old habit, and told Abimelech, king of Gerar, that Sarah his wife was his sister. We question how Abraham could have lied again and made the same mistake. Abraham grew spiritually as God’s friend and intercessor. But we realize that even mature servant of God like Abraham repeats his old sinful habit. We are not completely free from our old habit of sin though we are saved by the grace of Jesus. We must be awake spiritually not to fall into our old sinful habit through our prayer life. What was the consequence of his habitual lie? Then Abimelech said, “No problem, I will take your sister.” So he took her. How did Abraham feel when Sarah was taken? Maybe he shook his head again and again and said, “Oh, no. Not again. I am sorry, Sarah. I made the same mistake again.”  He had endangered God’s promise that Sarah would have a son that year. This could not happen if Abraham loses Sarah. Sarah might have born a son from Abimelech. It was like Abraham fumbling the ball before the end zone. God’s promise was in jeopardy. God intervened immediately to protect Sarah. God watches over his children 24-7 and intervenes in our life when we make a mistake.

When God warned Abimelech in verse 3 that he was as good as dead because he had taken a married woman, Abimelech humbly asked God’s mercy. He apologized to Abraham and Sarah and made restitution. Look at verse 17. “Then Abraham prayed to God, and God healed Abimelech, his wife and his slave girls so they could have children again.” God elevated Abraham’s position as a healer and prophet and prayer servant to Abimelech and his household. Even though Abraham was wrong and Abimelech seems to be much better, God stood on Abraham’s side and he honored Abraham as his servant. Why? God chose Abraham to save the world. Though Abraham made a mistake, God carried his promise according to his plan. There is no failure in God. God was faithful to keep his promise to Abraham in spite of his human mistake. Abraham learned that God was the Sovereign of all people. God opened his spiritual eyes to see God’s presence everywhere he went. God is God of omnipotent. This was a new beginning of Abraham’s spiritual growth.



This passage is the highlight of Abraham and Sarah’s life of faith. God kept his promise and Isaac was born. No word of God shall fall to the ground. For 25 years, God had trained Abraham to believe his promise.  God did not cancel his promise due to Sarah’ s old age. He fulfilled his promise at the appointed time. In chapter 17 God revealed his plan to Abraham again by saying, “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.” But Abraham laughed and said to himself in Gen 17:17, “Will a son be born to a man a hundred years old? Will Sarah bear a child at the age of ninety?” In 18:12 Sarah laughed to herself as she thought, “After I am worn out and my master is old, will I now have this pleasure?” They laughed out of despair. God rebuked her unbelief and said, “Is anything too hard for the Lord?” Nothing is too hard for God. Abraham was old, and Sarah old, and both as good as dead. But the word of promise was not dead. Look at verses 1 and 2. “Now the Lord was gracious to Sarah as he had said, and the Lord did for Sarah what he had promised. Sarah became pregnant and bore a son to Abraham in his old age, at the very time God had promised him.” God came to Sarah as he promised. Finally, God gave her a son named Isaac. It was the greatest day for Abraham and Sarah. Imagine how much senior citizen Sarah laughed while holding a baby Isaac. Sarah forgot all her past sufferings as a barren woman and her sorrow turned into a extreme joy. Now Sarah became pregnant and bore a son to Abraham. We can learn three things from God.

First, God’s grace. God was gracious to Sarah. Sarah felt she had a big hole in her heart because she could not bear a child to Abraham. She felt to be cursed as a woman. She felt to be a failure as a wife. Woman’s happiness comes from fruitfulness. Elizabeth the mother of John the Baptist shared the same testimony when she was barren in Luke 1:25. “She said,’ In these days he has shown his favor and taken away my disgrace among the people.’” By the grace of God Sarah became pregnant and bore a son to Abraham. In the same way, Hannah the mother of Samuel was sorrowful due to her barrenness. Her husband could not comfort her. Only God solved his barrenness and brought her joy and happiness through the birth of Samuel. God showed his shining grace to Sarah. God did not want Sarah to remain as a barren woman. He was gracious to her at his appointed time. God removed her shame and disgrace as an unfruitful woman by his grace. God lifted up Sarah to become a mother of many kings through the birth of Isaac. It is God who gives us his grace. Isaac was not the product of her human effort but the gift of God. Isaac is a miracle baby because God opened Sarah’s dead womb.  Missionary Sarah Chang really wanted to raise up one American shepherd to become a fruitful missionary. But it seemed to be an endless struggle to her when many potential candidates left her one after another without saying good-bye. But God was gracious to her at his appointed time. God sent Lawson Glenn to become her Isaac of faith. Once we were dead due to our transgressions and iniquities, by the grace of God we were saved through the blood of Jesus and became precious children of God. Praise God who was gracious to Sarah and to all of us.

Second, God’s appointed time.  Look at verse 2. “Sarah became pregnant and bore a son to Abraham in his old age, at the very time God had promised him.” When did God keep his promise? It was at the very time he had promised. God’s time is different from our time. It would have been good if God gave Isaac to Abraham 2 or 3 years later when he received God’s calling. But God waited for 25 years to fulfill his promise. To God timing is everything. God waited for Abraham to become a mature servant of God through 25 years of faith training. Abraham’s primary concern was to solve his no son problem. Abraham was interested in solving his immediate practical problem but God was interested in raising him up as a father of many nations and a man of faith for the generations to come. God wanted Abraham to grow as a spiritual giant to endure God’s salvation plan. If God gave him Isaac too soon, Abraham might not have experienced the depth of God’s power and love for all mankind. He might have become satisfied with God’s blessings and lost an opportunity to understand God’s heart to save the whole world. God expanded his small heart to have a big heart through 25 years faith training. Through patience training God broadened Abraham’s heart to be a vessel big enough to contain God’s blessing. God waited for Abraham to become his friend, prophet, prayer partner, and a father of many nations through many training. During 25 years of training, God babysat Abraham and waited and waited for him to grow as a man of faith. Finally, God’s time came and God kept his promise and brought Isaac to his family. How do I know God’s time then? Of course, we want to raise up disciples of Jesus quickly and receive the Bible teacher of the year award. But God seems to answer our prayers very slowly. Sheep do not care about our deep desire and they seem to grow so slowly or they seem not to grow at all. Then we become impatient and despair. In the same way we want to solve our marriage problem very quickly. When we look around, there is no marriage candidate. We complain, “How long should I wait, Lord?” But it is not God’s right time. We are not ready to endure God’s blessings yet. God knows when is the best time to bless us. We should not be disappointed when God is slow in answering our prayers. There is a reason God delays to fulfill his promise. God wait for us so that we can have enough faith to endure his blessing. Let’s learn how to wait for God’s appointed time in our life of faith.  

Third, God is Almighty.  Look at verse 5. “Abraham was a hundred years old when his son Isaac was born.” We never heard that 100 years old man had a son. But nothing is impossible with God. According to verse 5 it took 25 years for Abraham to have a son. God is faithful in keeping his promises. Surely God made Abraham a great nation and blessed him as a source of blessing. Truly God is God Almighty. He made the Red Sea become a dry ground. He made Aaron’s rod bud. He raised Jesus from the dead. Abraham was not a prefect man. He had many weaknesses and failures. In crisis he depended on Sarah too much, “Sarah, Where are you? I am dying. Help me.”  But one thing great about him was that he believed God’s promise whenever God told him. That made him a great man of faith and God was able to use him in his history. In many ways we are like Abraham. One moment we believe God’s promise that we will be a great nation, and then next moment, “Hey no way, I can not believe it, I am a man of many mistakes. I cannot feed even one sheep.” But the Lord did for Sarah what he had promised. God is God Almighty. Anything is possible to him. Though we cannot trust this changing world, we can trust God’s word of promise. He even kept his promise of salvation by sending his own son Jesus into this world. All we can do is to wait for God’s time. As a teenager, Sarah B. wants to drive a car eagerly. But she must wait for her drive license to do that because David B. will not give her a car key because he knows it is not the time for her to drive. God knows the right time to keep his promise.

Look at verses 6-7. Sarah leaped for joy because God brought her laughter. All her neighbors laughed together with her. It is God who brings us true laughter. We also laugh when we read this passage. Who imagined that Sarah in her 90 years age would nurse a child? It was unthinkable. It was unbelievable. It would have made the headline news all over the world. But it was true. Sarah was holding a child with her gray hairs. It was beyond human imagination. God’s work is beyond our imagination. Who would have believed that fun-loving Abraham Lee would become a missionary to China? God made us laugh when we think about the power of God. Do you believe that God will make us laugh when he will raise up 7 key members? Do you believe that God will make us laugh when he will raise up 12 disciples among GMU students? Among us God brought us laughter when M. Grace M. delivered a son Jeremiah. Anthony smiled from ear to ear when he held little Jeremiah and we all praised God who gave this miracle baby to Anthony and Grace. There is a saying, “All is well that ends well.” This is true. Our life can be measured how we end our life. Our life will be evaluated by the fruit we bear. Isaac means he laughs or fruit. Actually, Isaac was the fruit of Abraham’s faith of obedience. He was the symbol of victory of faith. What kind of fruit we bear is very important. Why? John 15:8 says, “This is to my Father’s glory, that you bear much fruit, showing yourselves to be my disciples.” We glorify God and prove that we are Jesus’ disciples through our fruitful life of faith.

There are two contrasting example of fruit bearing in Genesis. They are Lot and Abraham. They both received God’s calling and started a journey of faith. But there was a decision hour in Gen 13:9, “If you go to the left, I will go to the right, if you go to the right, I’ll go to the left.” Lot followed his worldly desire to enjoy the riches of the world while Abraham followed God’s promise. One ended in destruction while the other in joy and laughter. Each day we have a choice between God’s promise and the world. If we hold God’s promise and live by faith, we will have many Isaacs and laugh together with others. We will live with God forever and share his glory like Abraham. If we choose the world, we will end our life with sorrow and tragedy. Let’s follow Abraham’s life of faith and share the joy of fruitful life like Sarah. When we believe the promise of Jesus and wait for his second coming, we will become very fruitful and many campus students will be blessed.



Look at verse 8. “The child grew and was weaned, and on the day Isaac weaned Abraham helda great feast.” Isaac grew and was weaned. At that time a child was weaned at the age of three. Isaac was three years old boy and Ishmael became 17 years old teenager. On the day Isaac was weaned, Abraham held a great feast. But what happened in this happy day? Look at verse 9. “But Sarah saw that the son whom Hagar the Egyptian had borne to Abraham was mocking.” Here mocking means “despising” or “persecuting.” Ishmael, a strong teenager, almost a man, was obviously jealous of little Isaac. Isaac seemed to take away love and attention from Abraham and now he became fatalistic about his future. As prophesied in Gen. 16:12, so Ishmael was hostile toward Isaac and bullied and persecuted young Isaac and made fun of him. Look at verse 10. “And she said to Abraham, “Get rid of that slave woman and her son, for that slave woman’s son will never share in the inheritance with my son Isaac.” Sarah realized that Ishmael was too strong for Isaac and she asked Abraham to get rid of the slave woman and her son. This was Abraham’s sore spot.

Abraham was distressed, because it concerned his son whom he loved. He didn’t like a suggestion that seemed to come from Sarah’s jealousy. Look at verse 12. But God supported Sarah’s suggestion in this time and God told him not to be distressed, but to listen to Sarah in this matter. Sometimes Sarah’s advice was wrong like in Gen. 16, but other times it was right. Then what men should do? Should they listen to wife’s advice or not? Yes, most of the time, listen to her. You will not lose anything when you listen to your wife’s spiritual advice. God also promised him, “It is through Isaac that your descendants will be reckoned.” God also promised to take care of Hagar and Ishmael and bless them.

So Abraham overcame his strong sense of human obligation and human attachment; he trusted and obeyed God. He got up early in the morning, gave Hagar and Ishmael a skin of water and some food and sent them away. This seems to be a cruel thing to do. But it was actually the way of blessing for Hagar. Ishmael was old enough to take care of himself and his mother. If Abraham had insisted on taking care of them to the end, then God could not have cared for them or blessed them. God’s care and blessing were much better than anything Abraham could do for them.

Abraham knew that he must protect and care for the covenant son by any means, for he was not only a blessing to Abraham’s household-he carried with him God’s promise to bless the whole world through him. God was clear. Abraham’s real descendants must be children of the promise (Gal 3:29; Ro 4:18-24) not children of the flesh. Ishmael did not come from the promise of God but he was the product of Abraham’s impatience and human compromise. To cast out Ishmael was to cut away the last bit of human and worldly compromise from his life and heart. This was the fruit of real repentance and an affirmation of Abraham’s acceptance of God’s ways and God’s work. He had to deny himself. Something that hindered his spiritual growth died.

What are my Ishmael and my Isaac? Isaac refers to spiritual blessings from God and Ishmael refers to what we earned humanly or enjoyed before we met God. Ishmael seemed to be attractive and handsome to Abraham but he was the product of his compromise and flesh desire. Humanly speaking, Ishmael is good. But he is not the best. Isaac is the best because he is from God.   Before meeting Jesus, there was no Ishmael problem because everything was Ishmael. But when we find God’s plan and his will, then we have Ishmael problem. We struggle between God’s word and our Ishmael. Ishmael can be represented as our life of sin we enjoyed in the past. As we grow in faith, it will be a great burden to our spiritual life. There is a saying goes like this. “Good is the enemy of better and better is the enemy of the best.” Good or better things from the world hinder us to have the best. Apostle Paul said in Phil. 3:8, “What is more, I consider everything a loss compared to the surpassing greatness of knowing Christ Jesus my Lord, for whose sake I have lost all things. I consider them rubbish, that I may gain Christ.” Once Apostle Paul found the surpassing greatness of Jesus, the best gift from God, he considered every good things he enjoyed a loss. Saint Augustine gave up his hedonistic life he enjoyed when he found Jesus, the best gift from God. Hymn 456 says, “I’d rather have Jesus than anything this world affords today.” Once I was pursuing a good life with a caring wife and 2 sons and 1 daughter. But when I met Jesus, God gave me the best life as a humble shepherd for college students. When Steve H. graduated, it seemed good for Steve H. to go after money at Silicon Valley. It was a good idea to become next Bill Gate.  But it was not the best. The best was to grow in God and serve God’s flocks at College Park. God blessed him to grow as YDJ leader and a future professor shepherd. God gave him the best because he sent away good thing the world offered. Belssi C. could have looked for Chemical engineering job somewhere else as her better alternative. But her best was to stay and serve CBF children. God blessed her abundantly. As we know, light cannot coexist with darkness. Light comes, and the darkness disappears. Water and oil cannot mix together. Isaac comes, and then Ishmael must go. Last year I bought a new car SUV, Ford Explorer. Once I drove SUV, I lost desire to drive my old car. I gave up the old one because I have the best. We cannot have both Ishmael and Isaac. We have to send away one who is not from God. We cannot serve God and the world together. We have to give up good things to receive the best from God. We must let Ishmael go so that we can have spiritual environment where we can love God wholeheartedly. It is difficult to get rid of our Ishmael we enjoyed so long. But we must deny our flesh desire with painful decision and follow God’s word. Modern day Ishmael can be anything that hinders our spiritual growth in God. They can be too much T.V. or worldly friend or unbelieving family or video games or negative thinking or laziness or lustful desires, or humanism, or materialism or hedonism. There is no compromise between Isaac and Ishmael. We must be clear in sending away Ishmael so that we may grow in the promise of God.

In the desert, Hagar again met the God who sees and hears. She depended on God, and God was faithful to her, for Abraham’s sake. God enabled her to raise her son and he blessed their family.

When Abraham cast out Ishmael, he was ending his life of compromise. Fear went out of his heart. His relationships with those in his own family changed and his relationship with the unbelieving world also changed. Abimelech and his commander, Phicol, came to visit Abraham again. They greeted him “God is with you in everything you do. Now swear to me here before God that you will show me kindness...” Abraham’s exemplary life of faith moved the pagan king Abimelech. Abraham influenced him to see God in his life of faith. Abimelech recognized Abraham as God’s servant. And Abraham recognized himself as God’s servant. With his fear gone, he could confront Abimelech about a well that Abraham’s servants had dug, but which the Philistines had stolen. Abimelech apologized. Then, Abraham gave a gift to Abimelech as a sign that the well belonged to him. Abraham took the lead in their relationship. He met Abimelech as an equal.

After this, Abraham planted a tamarisk tree in Beersheba and called on the name of the Lord. This time he called God the Eternal God. This showed that Abraham learned that God controlled all human history beyond time and space. God is eternal. His spiritual victory over Abimelech did not make him proud; it made him more humbly dependant on God. His real victory was victory over himself through absolute obedience to God. I pray that we all may trust God’s promise to the end. Let’s read the key verse 21:1.