Genesis 17:15-27 By living in God’s perfect will today, we secure eternal blessings for tomorrow’s generations

Genesis 17:15-27

15 Then God said to Abraham, “As for Sarai your wife, you shall not call her name Sarai, but Sarah shall be her name. 16 I will bless her, and indeed I will give you a son by her. Then I will bless her, and she shall be a mother of nations; kings of peoples will come from her.” 

17 Then Abraham fell on his face and laughed, and said in his heart, “Will a child be born to a man one hundred years old? And will Sarah, who is ninety years old, bear a child?” 18 And Abraham said to God, “Oh that Ishmael might live before You!” 19 But God said, “No, but Sarah your wife will bear you a son, and you shall call his name Isaac; and I will establish My covenant with him for an everlasting covenant for his descendants after him. 

20 As for Ishmael, I have heard you; behold, I will bless him, and will make him fruitful and will multiply him exceedingly. He shall become the father of twelve princes, and I will make him a great nation. 21 But My covenant I will establish with Isaac, whom Sarah will bear to you at this season next year.” 22 When He finished talking with him, God went up from Abraham.

23 Then Abraham took Ishmael his son, and all the servants who were born in his house and all who were bought with his money, every male among the men of Abraham’s household, and circumcised the flesh of their foreskin in the very same day, as God had said to him. 24 Now Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin. 25 And Ishmael his son was thirteen years old when he was circumcised in the flesh of his foreskin. 26 In the very same day Abraham was circumcised, and Ishmael his son. 27 All the men of his household, who were born in the house or bought with money from a foreigner, were circumcised with him.


God makes it plain to Abraham that the heir of God’s everlasting covenant will come from Sarah. God’s divine announcement of Isaac’s conception is met with Abraham’s apparently incredulous laugh which God incorporated into the naming of Isaac. Upon Abraham’s mention of Ishmael, God in no uncertain terms set Isaac apart from all other sons as the rightful heir to Abraham’s promise. God has so determined that the heir of righteousness must in no uncertain terms come from Sarah, not by any surrogate. By living in God’s perfect will today, we secure eternal blessings for the generations of tomorrow.


As for Sarai your wife, you shall not call her name Sarai, but Sarah shall be her name.

When God speaks to Abraham concerning the promised heir, his heart cannot fully grasp it. God meant the heir to be coming from Sarah and not from Hagar or from any surrogate. Such grave misunderstandings arise because of the hardness of the heart and the corruption of human culture. Here, God speaks in explicit terms, … indeed I will give you a son by her.” God, in the same breath changes Sarai’s name to Sarah to reflect her new found identity (at the conception of the heir) as mother of the nations.

Then Abraham fell on his face and laughed, and said in his heart, “Will a child be born to a man one hundred years old? 

The reason that Abraham falls on his face can be attributed to his bewildered state of mind: Will a child be born to a man one hundred years old? The divine announcement flies in the face of physical impossibility which leads to an involuntary reaction. For Abraham, the frustration of having the promise dangled intermittently throughout these 23 years is too much for him to bear. Thus, he offers Ishmael as a pragmatic alternative: Oh that Ishmael might live before You! However, God who does not settle for anything less than His perfect plans looks pass the impotence of Sarah’s aged body and announces the imminent conception of the chosen heir. The name Isaac, literally means “and laughed” is picked to remind Abraham of God’s faithfulness vis-à-vis Abraham’s unbelief in bringing the promises to fruition. The covenant essentially guarantees the settlement of Abraham’s descendants in the land of Canaan.

As for Ishmael, I have heard you; behold, I will bless him, and will make him fruitful.

As a consolation, Abraham is assured that Ishmael is not left out of God’s blessing for he will father 12 princes and become a great nation. Nevertheless, God maintains that the covenant through which all the families of the earth will be blessed will be fulfilled through Isaac. It is important to note that the covenant with Isaac stands in contrast with the promise concerning Ishmael. God promises Isaac’s descendants an eternal inheritance and righteousness in God’s kingdom. As for Ishmael’s descendants, they will enjoy material blessings and an earthly glory albeit fleeting and transient.

Then Abraham took Ishmael his son, and all the servants who were born in his house and … circumcised the flesh of their foreskin in the very same day.

Abraham upon God’s departure, and having received the divine instruction, sets out to circumcise every male in his house that very day. This speaks of Abraham’s reverence towards God and that His instructions must at all cost be carried out. The human psyche demands expression of an inner renewal, an external mark that represents his newfound identity in relation to God. The act of circumcision creates an external sign of God’s covenantal protection while awaiting the internal sign of the Holy Spirit in the new covenant.


If we desire eternal blessing for our future generations, we have to live in God’s perfect will today.

Although Abraham succeeds in bearing a son through a surrogate, God’s eternal blessing is not in it. Not only is Sarah’s surrogate son rejected as heir apparent, Hagar’s descendants will in time incur wide ranging and far reaching consequences for Isaac’s descendants. If we desire eternal blessing for tomorrow’s generations, we must endeavour to live in God’s perfect will today. God’s holy schemes can never synergise with human devices no matter how brilliant they appear to be. Ishmael is proof that human devices can never forward the eternal purposes of God.

Many churchgoers especially the younger ones become impatient when it comes to considering the mysterious ways of God. They look for physical signs instead of an inner witness of divine approval. In fact most have the tendency to analyse God’s ways like they do with the sciences and with worldly issues. They assess their course of action by the intended results it produces. For God, the end certainly does not justify the means.

How then can believers discern God’s perfect will and to live in it?

We discern God’s perfect will by first casting out the spirit of the world and receiving the Spirit of God. The apostle Paul describes the things of the Spirit as foolishness to the natural man who operates in the spirit of the world (see 1 Corinthians 2:14). Therefore, in order to perceive the thoughts of God, one has to first reject the spirit of the world and receive the Spirit of God (see 1 Corinthians 2:12). When we meditate on the written word, the Holy Spirit brings to mind the reverberations of God’s thoughts and plans. God’s thoughts are readily available to the mind that is saturated with God’s word, to be unpacked and made relevant to current circumstances (see 1 Corinthians 2:13). How do we know if we possess the spirit of the world or the Spirit of God? The below are some observations:

  • The spirit of the world follows the patterns of popular culture and successful people.
  • The Spirit of God causes us to pursue the manner in which Jesus lives.
  • The spirit of the world focuses on performance and building an appearance of success.
  • The Spirit of God focuses on building foundations of truth and character.
  • The spirit of the world emphasises precision and correctness of doctrine.
  • The Spirit of God focuses on the prophetic call of being like Jesus and operating in His full capacity; His wisdom, love and power.
  • The spirit of the world causes man to pursue his personal dreams and ambitions.
  • The Spirit of God causes man to be contented and to embrace his lot in God’s perfect will.

Through Christ, Isaac’s eternal covenant of righteousness is made available to all who believe.

Isaac’s blessing stands in stark contrast with Ishmael’s in that it carries the eternal glory and righteousness of God. Ishmael’s blessing is earthly, fleshly and fleeting whereas Isaac’s is heavenly, spiritual and eternal. In the days of the Old Testament, Isaac’s eternal covenant of righteousness is given to a chosen few. But in the last days, the eternal glory of God is freely available to all who are willing to pursue God’s righteousness through the blood of Christ.

Many churchgoers prefer Ishmael’s earthly blessing over Isaac’s eternal blessing of righteousness. Even as their mouth confess Christ as Lord, their hearts hunger after the fleeting riches and pleasures of the world. How do we obtain the eternal blessing of Abraham and Isaac? God speaks to Abraham, “Walk before Me, and be blameless.” Genesis 17:1. By living in the manner that Christ lives and in making disciples, we obtain the eternal blessings of Abraham.


Are you accustomed to helping God work out His plans in your life? Do you feel insecure without a plan at hand? While some err in the direction of lethargy, most with their unstable minds and troubled hearts, resort to the reading of physical circumstances as signs to determine God’s will for their lives. Meditate on the word daily, so that you may not be misled by the spirit of the world. By being filled with the Spirit of God, you may discern God’s perfect will and live in it.

Dear Lord, I desire to live in your perfect plans so that I may see enduring blessedness in future generations. As I reject the spirit of the world, I open my heart to receive the Spirit of God. Reveal your plans and your truths to me so that I may walk in it. Prepare me for greater works and send me when I am found ready. In Jesus’ name I pray. Amen.

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