Sermon: Genesis 21: The Promises Of God Fulfilled In The Birth of Isaac

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Old Testament Reading: Genesis 21

“The LORD visited Sarah as he had said, and the LORD did to Sarah as he had promised. And Sarah conceived and bore Abraham a son in his old age at the time of which God had spoken to him. Abraham called the name of his son who was born to him, whom Sarah bore him, Isaac. And Abraham circumcised his son Isaac when he was eight days old, as God had commanded him. Abraham was a hundred years old when his son Isaac was born to him. And Sarah said, ‘God has made laughter for me; everyone who hears will laugh over me.’ And she said, ‘Who would have said to Abraham that Sarah would nurse children? Yet I have borne him a son in his old age.’ And the child grew and was weaned. And Abraham made a great feast on the day that Isaac was weaned. But Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, laughing. So she said to Abraham, ‘Cast out this slave woman with her son, for the son of this slave woman shall not be heir with my son Isaac.’ And the thing was very displeasing to Abraham on account of his son. But God said to Abraham, ‘Be not displeased because of the boy and because of your slave woman. Whatever Sarah says to you, do as she tells you, for through Isaac shall your offspring be named. And I will make a nation of the son of the slave woman also, because he is your offspring.’ So Abraham rose early in the morning and took bread and a skin of water and gave it to Hagar, putting it on her shoulder, along with the child, and sent her away. And she departed and wandered in the wilderness of Beersheba. When the water in the skin was gone, she put the child under one of the bushes. Then she went and sat down opposite him a good way off, about the distance of a bowshot, for she said, ‘Let me not look on the death of the child.’ And as she sat opposite him, she lifted up her voice and wept. 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. He lived in the wilderness of Paran, and his mother took a wife for him from the land of Egypt. At that time Abimelech and Phicol the commander of his army said to Abraham, ‘God is with you in all that you do. Now therefore swear to me here by God that you will not deal falsely with me or with my descendants or with my posterity, but as I have dealt kindly with you, so you will deal with me and with the land where you have sojourned.’ And Abraham said, ‘I will swear.’ When Abraham reproved Abimelech about a well of water that Abimelech’s servants had seized, Abimelech said, ‘I do not know who has done this thing; you did not tell me, and I have not heard of it until today.’ So Abraham took sheep and oxen and gave them to Abimelech, and the two men made a covenant. Abraham set seven ewe lambs of the flock apart. And Abimelech said to Abraham, ‘What is the meaning of these seven ewe lambs that you have set apart?’ He said, ‘These seven ewe lambs you will take from my hand, that this may be a witness for me that I dug this well.’ Therefore that place was called Beersheba, because there both of them swore an oath. So they made a covenant at Beersheba. Then Abimelech and Phicol the commander of his army rose up and returned to the land of the Philistines. Abraham planted a tamarisk tree in Beersheba and called there on the name of the LORD, the Everlasting God. And Abraham sojourned many days in the land of the Philistines.” (Genesis 21, ESV)

New Testament Reading: Galatians 4:21–31

“Tell me, you who desire to be under the law, do you not listen to the law? For it is written that Abraham had two sons, one by a slave woman and one by a free woman. But the son of the slave was born according to the flesh, while the son of the free woman was born through promise. Now this may be interpreted allegorically: these women are two covenants. One is from Mount Sinai, bearing children for slavery; she is Hagar. Now Hagar is Mount Sinai in Arabia; she corresponds to the present Jerusalem, for she is in slavery with her children. But the Jerusalem above is free, and she is our mother. For it is written, ‘Rejoice, O barren one who does not bear; break forth and cry aloud, you who are not in labor! For the children of the desolate one will be more than those of the one who has a husband.’ Now you, brothers, like Isaac, are children of promise. But just as at that time he who was born according to the flesh persecuted him who was born according to the Spirit, so also it is now. But what does the Scripture say? ‘Cast out the slave woman and her son, for the son of the slave woman shall not inherit with the son of the free woman.’ So, brothers, we are not children of the slave but of the free woman.” (Galatians 4:21–31, ESV)

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Introduction

The text that we are considering this morning is divided into three parts. One, the story of the birth of Isaac found in Genesis 21:1-7. Two, the story of the casting away of Ishmael found in verses 8-21. And three, the story of the covenant transacted between Abraham and Abimelech is found in verses 22-34. 

Naturally, the sermon today will have three points which correspond to these three stories. First, we will consider the promises of God fulfilled in the birth of Isaac. Secondly, we will consider the pain caused by the sin of Abraham and Sarah committed years earlier (along with God’s mercies). And three, we will consider the faithfulness of the LORD to be present with his covenant people in their sojourning.   

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The Promises Of God Fulfilled In The Birth Of Isaac

First, let us look upon verses 1 through 7 to consider the promises of God fulfilled in the birth of Isaac. 

In verses 1 and 2 we finally hear the news that we have been waiting for. “The LORD visited Sarah as he had said, and the LORD did to Sarah as he had promised. And Sarah conceived and bore Abraham a son in his old age at the time of which God had spoken to him.” (Genesis 21:1–2, ESV)

The tension concerning Sarah’s barrenness has been building ever since it was first mentioned in verse 30 of chapter 11. There we read, “Now Sarai was barren; she had no child” (Genesis 11:30, ESV). And that tension has increased with the passing of time and with each promise uttered by the LORD concerning a child for Abraham and Sarah. Those promises which were reiterated and clarified from time to time were comforting, no doubt. But they also increased the anticipation. When, LORD? When will Sarah and Abraham have this child? Time is certainly running out!

Finally, the time has come. The text says, “The LORD visited Sarah”. This indicates that the birth of Isaac was supernatural. It was not a virgin birth, as it was with the birth of the Christ. Indeed, Isaac was conceived by the ordinary means of procreation. But it was supernatural and miraculous none the less. The LORD visited Sarah. She was now 90 years old. She had been barren all her life. Abraham was 100. And the LORD miraculously enabled her to conceive.

When we read verses 1 and 2 did you notice the emphasis upon this being in fulfillment to the promises of God?  Hear it again: “The LORD visited Sarah as he had said, and the LORD did to Sarah as he had promised. And Sarah conceived and bore Abraham a son in his old age at the time of which God had spoken to him” (Genesis 21:1–2, ESV). Three times the text emphasizes that these things happened in fulfillment to God’s promises.  

Have you ever wondered why the LORD made Sarah and Abraham wait so long for their son? I suppose we may never know all of the reasons, for there are “secret things [that] belong to the LORD our God, but the things that are revealed belong to us and to our children forever, that we may do all the words of this law” (Deuteronomy 29:29, ESV). But I think it is safe to say that at least three things were being accomplished through the waiting. 

One, the faith of Abraham and Sarah was being tested. Would they go on believing the LORD when the fulfillment of his promises seemed impossible to them? Would they persevere in the faith with the passing of time? Their faith was being tested, so that it might also be strengthened. Faith that is true gets stronger when it is tried and tested. Abraham and Sarahs faith grew stronger as it was tested over time. 

APPLICATION: Friends, the LORD allows our faith to be tested from time to time, doesn’t he? This he does in a variety of ways. But if our faith is true, the testing is it is for the purpose of strengthening our faith. Just as the body and mind will not grow stronger if they are not tested, neither will our faith. Faith, if it is true faith, grows stronger when it is tested. Faith, if it is false faith, will wither before the heat of trials and tribulations. 1 Peter 1:3-7 says, “Blessed be the God and Father of our Lord Jesus Christ! According to his great mercy, he has caused us to be born again to a living hope through the resurrection of Jesus Christ from the dead, to an inheritance that is imperishable, undefiled, and unfading, kept in heaven for you, who by God’s power are being guarded through faith for a salvation ready to be revealed in the last time. In this you rejoice, though now for a little while, if necessary, you have been grieved by various trials, so that the tested genuineness of your faith—more precious than gold that perishes though it is tested by fire—may be found to result in praise and glory and honor at the revelation of Jesus Christ” (1 Peter 1:3–7, ESV). 

Abraham and Sarah’s faith was tested as the fulfillment to the promise was delayed. 

Two, the ability of the LORD to bring life from death was put on display as Sarah and Abraham waited long for their promised son. 

You would do well to notice that barrenness is a bit of a theme in the book of Genesis. The earth was barren (that is, empty and void) when it was first created, and yet the LORD formed it into a place suitable for life, particularly human life. For 90 years Sarah was barren. Rachel, the wife of Jacob (the grandson of Abraham) was also barren (see Genesis 29:31). In each instance the LORD overcomes barrenness and makes that which is dead to live.  

APPLICATION: Brothers and sisters, the LORD has done the same for you and for me — indeed, for all who have faith in Christ Jesus. He had taken that which is dead and he has made it alive. “You were dead in the trespasses and sins in which you once walked… But God, being rich in mercy, because of the great love with which he loved us, even when we were dead in our trespasses, made us alive together with Christ—by grace you have been saved…” (Ephesians 2:1–2, 4-5, ESV). What the LORD did for Sarah’s womb, he has also done for your soul. You were dead (according to the soul), but God has made you alive in Christ. He has “visited you”, and by his Spirit he has enabled you to believe. He has opened your blind eyes, unstopped your deaf ears, and has breathed the breath of life into your lifeless soul — by grace you have been saved. 

The ability of the LORD to bring life from death was put on display as Sarah and Abraham waited long for their promised son.

Three, the faithfulness of the LORD was also demonstrated to Abraham, and through him, to the world as  he and Sarah waited long for their promised son.

The LORD is faithful. He always keeps his promises. He cannot lie or change his mind. The people of God sometimes doubt his faithfulness with the passing of time. But the story of the long awaited birth of Isaac demonstrates that God will  always keep his promises, even if the wait seems unreasonably long. 

Brothers and sisters, this is how Paul the Apostle interpreted and applied the story of the birth of Isaac in his epistle to the Romans, chapter 4 verses 16-22. He writes, “That is why it depends on faith, in order that the promise may rest on grace and be guaranteed to all his [Abraham’s] offspring—not only to the adherent of the law but also to the one who shares the faith of Abraham, who is the father of us all, as it is written, ‘I have made you the father of many nations’—in the presence of the God in whom he believed, who gives life to the dead and calls into existence the things that do not exist. In hope he believed against hope, that he should become the father of many nations, as he had been told, ‘So shall your offspring be.’ He 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. No unbelief made him waver concerning the promise of God, but he grew strong in his faith as he gave glory to God, fully convinced that God was able to do what he had promised. That is why his faith was ‘counted to him as righteousness.’” (Romans 4:16–22, ESV)

Brothers and sisters, the promises of God were indeed fulfilled in the birth of Isaac.  The LORD was found  faithful. And Abraham obeyed the LORD. He “circumcised his son Isaac when he was eight days old, as God had commanded him” (Genesis 21:4, ESV), for circumcision was the sign and seal of that covenant which the LORD had transacted with Abraham. 

And notice the joy. Indeed, it is a very joyous thing to see the fulfillment of the promises of the LORD. “And Sarah said, ‘God has made laughter for me; everyone who hears will laugh over me.’ And she said, ‘Who would have said to Abraham that Sarah would nurse children? Yet I have borne him a son in his old age’” (Genesis 21:6–7, ESV).

The last time that we heard of Sarah’s laughter, it was laughter of unbelief. Here is a joyous laughter. By the way, the name Isaac means, he laughs. Indeed, the birth of Isaac caused Sarah to laugh with joy. Not only was this the joy of having a child after so many years of barrenness, but also joy in seeing the promised of God fulfilled in their proper time.  

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The Pain Caused By The Sin Of Abraham And Sarah

From the joy of verses 6 and 7 we transition rather abruptly to the pain and sadness of verses 8 through 21. And that brings us to the secondly point of the sermon today. Brothers and sisters, consider carefully the pain caused by the sin of Abraham and Sarah committed years earlier (along with God’s mercies).

Perhaps as many as three years had passed from the birth of Isaac to the events narrated in verses 8 through 21, for verse 8 says, “And the child grew and was weaned. And Abraham made a great feast on the day that Isaac was weaned” (Genesis 21:8, ESV). Children in that culture were sometimes weaned as late as three years of age. Perhaps Isaac was 3, and that would put Ishmael at the age of 16. Ishmael is called a “boy” and a “child” in these passage, but the Hebrew word can also be translated as “young man”. Indeed, we are to picture Ishmael as a young man — probably 16 years of age. 

In verses 9 we learn that at the feast that Abraham made for Isaac,  “Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, laughing” (Genesis 21:9, ESV). The Hebrew word translated “laughing” here in verse 9 is that same word that was translated as “laugh” in verse 6. Clearly this is a play on words, for the Hebrew word can either mean to laugh with joy, or to laugh in a mocking way. Sarah laughed with joy at the birth of Isaac, but Ishmael laughed to mock Isaac, the son of promise. 

Notice that this is the interpretation that the New Testament gives, for Paul refers to this laughter of Ishmael as persecution in Galatians 4:29, saying,  “But just as at that time he who was born according to the flesh persecuted him who was born according to the Spirit, so also it is now” (Galatians 4:29, ESV). This was not joyous laughter. This was not innocent laughter. Ismael was mocking the boy and was known to persecute him. Sarah knew this intuitively, and so she, being concerned for the welfare of her son, demanded  that Ishmael, the son of the bondwoman, be sent away from the son of promise. Verse 10: “So she said to Abraham, ‘Cast out this slave woman with her son, for the son of this slave woman shall not be heir with my son Isaac’” (Genesis 21:10, ESV).

Notice that this grieved Abraham to core. In verse 11 we read, “And the thing was very displeasing to Abraham on account of his son” (Genesis 21:11, ESV). No doubt, Abraham loved Ishmael very much. The thought of sending him away with Hagar at the age of 16 grieved his heart. 

APPLICATION: Friends, have you noticed that our sin often has consequences? Sin makes life messy and complicated. Sin entangles. It wounds. It divides. Sin, which is any lack of conformity unto or violation of the law of God, always has consequences which grieve the heart and infuse life with a bitter taste. Do you want a good and pleasant life? Then keep God’s law! Notice I did not say that life would be without struggle altogether if we keep God’s law, for even the righteous suffer in this world. But I am saying that an obedient life is a blessed life. To walk with God and in obedience to him in this world is a blessed experience. It produces a blessed life, even if it is a difficult  life marked by suffering. Indeed the scriptures are true: “Blessed is the man who walks not in the counsel of the wicked, nor stands in the way of sinners, nor sits in the seat of scoffers; but his delight is in the law of the LORD, and on his law he meditates day and night. He is like a tree planted by streams of water that yields its fruit in its season, and its leaf does not wither. In all that he does, he prospers” (Psalm 1:1–3, ESV).

16 years earlier Abraham and Sarah decided that God needed their help. They concocted a plan involving a Sarah’s bondwoman, Hagar. Perhaps God would give Abraham a son through her, they reasoned. After all, it was clearly impossible for Sarah to have a son. And now Abraham and Sarah, Hagar and Ishmael are reaping some of that bad fruit which sown so many years earlier. It’s a sad story, isen’t it? It would probably be a good idea to put yourself in the sandels of each of the characters and to look at the situation from their unique perspective. And if you do you will see that the situation is sad and painful for each of them, but in different ways. I’m sure that each one of them — Abraham and Sarah, Hagar and Ishmael  — shed many tears in the days in which the bitter fruit of the sin of Abraham ripened. 

APPLICATION: Brothers and sisters, I wonder if you will learn from this story? I wonder if you will learn from the scriptures, that the wages of sin is death?  Or will you be one of those who has to learn the hard way, that is to say, by  experience. You do understand that there are two ways to learn this truth that sin is bitter, don’t you? You can learn it by believing, or you can learn it by experience. How much better it is to learn it by believing. 

God’s word says, “My son, if you receive my words and treasure up my commandments with you, making your ear attentive to wisdom and inclining your heart to understanding; yes, if you call out for insight and raise your voice for understanding, if you seek it like silver and search for it as for hidden treasures, then you will understand the fear of the LORD and find the knowledge of God. For the LORD gives wisdom; from his mouth come knowledge and understanding; he stores up sound wisdom for the upright; he is a shield to those who walk in integrity, guarding the paths of justice and watching over the way of his saints. Then you will understand righteousness and justice and equity, every good path; for wisdom will come into your heart, and knowledge will be pleasant to your soul; discretion will watch over you, understanding will guard you, delivering you from the way of evil, from men of perverted speech, who forsake the paths of uprightness to walk in the ways of darkness, who rejoice in doing evil and delight in the perverseness of evil, men whose paths are crooked, and who are devious in their ways. So you will be delivered from the forbidden woman, from the adulteress with her smooth words, who forsakes the companion of her youth and forgets the covenant of her God; for her house sinks down to death, and her paths to the departed; none who go to her come back, nor do they regain the paths of life. So you will walk in the way of the good and keep to the paths of the righteous. For the upright will inhabit the land, and those with integrity will remain in it, but the wicked will be cut off from the land, and the treacherous will be rooted out of it.” (Proverbs 2:1–22, ESV)

I’ll let you read this story again for yourself so that you can more thoroughly consider all of the pain that the sin of Abraham caused once that bad fruit had fully ripened. But there is something else I would like to emphasize before moving on to the third and final point of the sermon, and that is that God shows mercy to his covenant people even as they suffer under the consequences of their own sin. 

Where do I see that in this text? Well, in two places. 

One, the LORD did speak to Abraham to give him clarity over what he should do as he agonized over the decision that was before him. Verse 12: “But God said to Abraham, ‘Be not displeased because of the boy and because of your slave woman. Whatever Sarah says to you, do as she tells you, for through Isaac shall your offspring be named. And I will make a nation of the son of the slave woman also, because he is your offspring’” (Genesis 21:12–13, ESV). God, in his mercy, spoke to Abraham to help him know what to do as he stood perplexed in this messy situation. And he also comforted him concerning Ishmael, whom he undoubtably loved as a son, saying, “I will make a nation of” him, “because he is your offspring.”

Two, I also see the mercy of God displayed in his care for Hagar and Ishmael. Evidently they got lost in the wilderness. They found themselves without water. Hagar thought Ismael would die, so she left him in the shade and walked away, because she could not bear to witness the death of her son. But what does the text say? Verse 16: Hagar “lifted up her voice and wept. 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…” (Genesis 21:16–20, ESV).

Do you see that in the midst of all of this pain and suffering which was the result of sin, God was merciful to his covenant people. (If I had more time I would go to Galatians 4:21 and following to show how Paul interpreted this event. When he looks at Isaac the son of Sarah and Ishmael the son of Hagar he sees two covenants represented. This agrees with what I have said earlier about considering Abraham in a double capacity. There are two aspects to the Abrahamic Covenant — one fleshly and one spiritual; one earthly and one heavenly. In Abraham there are two kinds of offspring. There are children of Abraham according to the flesh, and there are children of Abraham according to faith in the promise. Ishmael descended from Abraham according to the flesh, but he laughed at the promise, not because he rejoiced in it, but to mock it. Isaac was the child of promise. Through him the nations of the earth would be blessed.  And what did the Apostle to Christians, most of the being Gentiles and not Jews? “So, brothers, we are not children of the slave but of the free woman” (Galatians 4:31, ESV). This is all very important if we are to understand the story of the Bible and know the relationship between the Abrahamic, Mosaic and New Covenant’s. But explaining all of that would take too much time. Perhaps I’ll recommend a book on that subject soon.) For now I am content to say, brothers and sisters, consider the mercy of God shown to sinners even as they agonize under the weight of sins which they themselves committed. 

APPLICATION: This should not be difficult for you to apply to your own lives. I have already shown you that sin carries consequences. And you probably thinking to yourself, no kidding! I’ve experienced that first hand! But here I am emphasizing another more comforting truth — God does not abandon those who belong to him. He does not turn his back on them because they have sinned. Far from it! He is in fact full of mercy and grace. He draws near to his covenant people the sustain them, even as they suffer the consequences of their sin. I cannot say the same for the one who is not in Christ. Those not in Christ suffer in this world, but without the hope that the Father is using it for their God. But those in Christ know, “that for those who love God all things work together for good, for those who are called according to his purpose” (Romans 8:28, ESV). And we are encouraged that even the discipline of the LORD is for our good. Hebrews 12:5 askes, “Have you forgotten the exhortation that addresses you as sons? ‘My son, do not regard lightly the discipline of the Lord, nor be weary when reproved by him. For the Lord disciplines the one he loves, and chastises every son whom he receives.’ It is for discipline that you have to endure. God is treating you as sons. For what son is there whom his father does not discipline? If you are left without discipline, in which all have participated, then you are illegitimate children and not sons. Besides this, we have had earthly fathers who disciplined us and we respected them. Shall we not much more be subject to the Father of spirits and live? For they disciplined us for a short time as it seemed best to them, but he disciplines us for our good, that we may share his holiness. For the moment all discipline seems painful rather than pleasant, but later it yields the peaceful fruit of righteousness to those who have been trained by it. Therefore lift your drooping hands and strengthen your weak knees…” (Hebrews 12:5–12, ESV)

Brothers and sisters, our sin has consequences. It produces turmoil and pain. But God is gracious still. He often uses the “natural consequences” (so called) of our sin to disciple us if we are his children. And this he does because he loves us in Christ Jesus.  

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The Constancy Of The LORD To Be Present With His Covenant People In Their Sojourning   

The thirdly and final point will have to be very brief. As we look upon verses 22 through 34 let us simply consider the constancy of the LORD to be present with his covenant people in their sojourning. 

Here in this story Abimelech and the commander of his army come to meet with Abraham to enter into a treaty with him.  Though more could be said, notice three things. 

One, in verse 22 Abimelech and his commander approached Abraham saying, “God is with you in all that you do” (Genesis 21:22, ESV). Even non-believing king was able to recognize that God was with Abraham. In other words, Abraham was blessed of the LORD! 

Two, this is to be contrasted with what we just learned about Ismael. Ishmael, the son of the flesh, mocked the son of promise. He thought little of the blessing of the LORD upon the house of Abraham. But Abimelech the foreign king saw it. He saw that Abraham was blessed of God. This seems to indicate that the same sort of thing will happen in the future. Some who would be born from Abraham’s loins would be like Ishmael who misunderstood mocked the promises of God made to him and the blessing of God that were upon him. But others who were not born from him — who not of his clan, but were of the nations — would call Abraham blessed. This is indeed how things would go within ethnic Israel and with the grafting in of the gentiles under the New Covenant. Read the New Testament and see. 

Three, the text concludes with these words, “And Abraham sojourned many days in the land of the Philistines” (Genesis 21:34, ESV). This reminds us that Abraham was promised, not only a son, but also a land. The land promise was still unfulfilled — he owned not a sliver. And yet Abraham went on to sojourn amongst the Philistines walking by faith and not by sight. 

 APPLICTAION: Brothers and sisters, how is your walk? Are you walking by faith and not sight? Are you living for the world to come? Is your hope in the new heavens and new earth, in which righteousness dwells? My prayer for us is that we would “lay aside every weight, and sin which clings so closely, and let us run with endurance the race that is set before us, looking to Jesus, the founder and perfecter of our faith, who for the joy that was set before him endured the cross, despising the shame, and is seated at the right hand of the throne of God” (Hebrews 12:1–2, ESV).

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Conclusion 

Almighty God, grant that the words which we have heard today, with our outward ears, may by your grace be so grafted inwardly in our hearts, that they may bring forth in us the fruit of good living, to the honor and praise of your name, through Jesus Christ our Lord. Amen.  

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