Genesis Bible Study (God's Grace To Overcome)

Genesis 20-21, Sin Again


One of the most frustrating parts of walking with God is the problem of repetitive sin. It is frustrating to see how difficult it is to overcome various temptations. We usually have a weakness that Satan exploits repeatedly. We commit ourselves to doing better yet we fail again. This failure can cause us to think that we are the only ones who are having difficulty with a particular sin. But this struggle of faith is not unique. We have the tendency to perceive Abraham to be the superhero of faith. But a closer examination of the life of Abraham shows that he truly is like us in the dealing with the challenges of faith. Along with our examination of Abraham we are able to learn more about the great character of God that is revealed to us even in the book of Genesis.

Same Sin, New Day (Genesis 20)

Abraham goes to live in the area of Gerar. When he arrives he does the exact same thing he did in Genesis 12. Rather than saying that Sarah is his wife, he says that Sarah is her sister. The result is also the same. Abimelech the king of Gerar took Sarah from Abraham. The same situation led to the same failure. As hard as it is to believe that Abraham falls into the same trap, all we need to do is look at our own lives and see how easy this is to do.

God comes to Abimelech in a dream and tells him that he is a dead man for taking another person’s wife. Abraham’s faithlessness has put another’s life in jeopardy. How we need to see that our sins are not affecting ourselves alone! Our sins and our faithlessness affect so many people. Abraham did not know that God was going to do this. We fail to realize how far reaching our sins impact others. We are devastating spouses, children, parents, friends, and co-workers. We are damaging relationships in the church. We are even harming people that we many hardly know or have never met.

How often God is trying to show us that are sins are damaging our own souls and the lives and souls of others! Further, God is trying to open our eyes to see that we need God to save us from ourselves. We do not know best. We are darkened in our thinking and our understanding.

Now this I say and testify in the Lord, that you must no longer walk as the Gentiles do, in the futility of their minds. They are darkened in their understanding, alienated from the life of God because of the ignorance that is in them, due to their hardness of heart. (Ephesians 4:17–18 ESV)

We know the promises of God. The problem is with the practical application of God’s promises to the details and difficulties of our daily walk. So God must come to rescue us from our darkened minds. Amazingly, again this is what God does. God comes to Abraham and Sarah’s rescue by telling Abimelech the truth that Abraham concealed. The hope of the world is that God desires to intervene and rescue. What a grace from God to intervene in the face of our sinfulness! In our failure God remains faithful and gives us the opportunity to turn our lives back to him. God wants us to see his grace and faithfulness. This picture of God’s faithfulness continues into Genesis 21.

Faithful God (Genesis 21)

Notice how chapter 21 opens. “The Lord did to Sarah as he had promised.” After the sin of Abraham, God continues to keep his word. Notice the same point in verse 2. “And Sarah conceived and bore Abraham a son in his old age at the time of which God had spoken to him.” God did exactly as he said. The time which God said is the time in which God returned. God does not come to Abraham and Sarah, telling them that because they blew it with this last sin and their lack of faith, the promises are nullified. God does not retract his covenant to Abraham because of his sin. This is a staggering thought: we cannot “outsin” God. Our times of weakness and sinfulness do not end our hope. God sent his Son to bring us hope, not to take away our hope. We saw this hope in the Gospel of John.

For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him. Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God. (John 3:17–18 ESV)

The apostle Paul wrote to the Romans concerning this hope.

Now the law came in to increase the trespass, but where sin increased, grace abounded all the more, so that, as sin reigned in death, grace also might reign through righteousness leading to eternal life through Jesus Christ our Lord. (Romans 5:20–21 ESV)

There is nothing greater to read than: “where sin increased, grace abounded all the more.” Not only is God gracious toward us in spite of our sins, but he is gracious to reverse our fortunes and situation. Notice how Sarah expresses this in verse 6, after Isaac is born. “God has made laughter for me; everyone who hears will laugh over me.” Sarah has gone from hopelessness to joy and laughter for what God has done for her. She has experienced a complete life reversal by the hand of God. What was laughter to Abraham and Sarah to think that they would have a child at such an old age has now caused the world to laugh with pleasure over what God has done for them.

Then God gives another picture of his faithfulness. There is a conflict in Abraham’s family as Ishmael appears to be mocking Isaac (21:8-9). Sarah instructs Abraham to cast Hagar and Ishmael out of the house. Abraham is troubled by this, and obviously so for this is his son. But God tells him to listen to Sarah for God will make a nation out of Ishmael. This does not look good for Hagar and Ishmael. They are sent into the desert of Beersheba with bread and a skin of water. This is not enough to survive on at all. In verse 16 we see that Hagar believes Ishmael is near death and lays him down under a bush (remember he is about 13 years old). But notice what God says in verses 17-20.

And God heard the voice of the boy, and the angel of God called to Hagar from heaven and said to her, “What troubles you, Hagar? Fear not, for God has heard the voice of the boy where he is. Up! Lift up the boy, and hold him fast with your hand, for I will make him into a great nation.” Then God opened her eyes, and she saw a well of water. And she went and filled the skin with water and gave the boy a drink. And God was with the boy, and he grew up. He lived in the wilderness and became an expert with the bow. (Genesis 21:17–20 ESV)

God had made a promise that Ishmael would be blessed by God, would be fruitful, and he would greatly multiply. Further, he would father twelve princes and make him into a great nation (Genesis 17:20). Even though Hagar and Ishmael are cast out, they will be blessed. They will be made into a great nation. Ishmael is not going to die in the desert. Hope is extended because God keeps his promises. Even in the face of sin, God keeps his promises.


His faithfulness in our failure is staggering. Yet the scriptures proclaim this glorious aspect of God repeatedly (1 Corinthians 1:9; 10:13; Hebrews 2:17; 10:23; 1 Peter 4:19; 1 John 1:9). Please make this personal. God is faithful to you. This was personal to Abraham and Sarah. God is faithful to forgive you of your sins and cleanse you of all unrighteousness (1 John 1:9). God is faithful to you and will not let you be tempted beyond your ability (1 Corinthians 10:13). Even in the face of our sins, God is faithful. How wonderful it is that we have a faithful high priest! We need someone to stand in on our behalf because of our sinfulness.

The faithfulness of God is the ground we need to stand on to fight sin. Looking at God’s faithfulness becomes the catalyst of transformation in our lives from serving our sinful desires to serving our faithful God who gives us life. Look at his faithfulness. Look at his faithfulness. Look at his faithfulness. Put your eyes on the cross to see the ultimate display of his faithfulness to you. We cannot expect any life change or begin any pursuit of holiness unless we have our eyes on the cross and our minds in God’s word reading about the steadfast love and mercy of the Lord. Our forgetfulness is what kills us spiritually on this journey. We forget that we are condemned in our sins. We forget that we are doomed from our actions. We forget that we have no hope in ourselves. We forget that the only reason we just took a breath is because God granted it. Get your eyes of the faithfulness of God. See all that he has done. Look at the work he has done in your life. Look at the transformation he has done on your heart. God transforms those who will put their trust in him. God stands ready in his steadfast love toward those who will cry out to the Lord. Abraham and Sarah’s life is completely changed by the promises of God. Hagar and Ishmael’s lives are sustained by the Lord in the midst of the desert. Will you be completely changed by God’s faithful promises? Will you submit your life to him today?

Share on Facebook
Scroll to Top