Genesis 21

The story

We first met Abraham back in chapter 12 when he was 75 years old. That’s when God instructed him to leave his father’s home and to go to the land God was going to show him. And God promised that Abraham would have so many descendants that all his offspring would become a great nation. Well, finally, 25 years later, Abraham and his wife Sarah have a son. And they gave this child the name ‘Isaac’ which means ‘he laughs’. This, of course, was a very suitable name given the circumstances of the boy’s birth. Sarah — do you remember? — laughed when she heard the news — announced to her by the Lord himself — that she would give birth in her old age. The very idea seemed so incredible to her. And now, with the birth of her son, she laughed again, but this time she laughed with joy, because of this wonderful thing that has taken place. She said:

Who would have said to Abraham that I would nurse children? Yet I have borne him a son in his old age.

We can imagine her joy, can’t we? However, there is someone else who is laughing in this chapter. On the day that Isaac was weaned — and that could happen when the boy was around three years old — a feast was held to celebrate this important day. But Sarah noticed that Ishmael — who was Abraham’s child by his servant Hagar and who was by now a teenager — was laughing or, as the NIV puts it in verse 9, he was ‘mocking’. His is a mocking laugh. It’s a sarcastic laugh and he’s laughing at what was going on.

Now that’s all the text says about it and it doesn’t make clear who or what he’s mocking or why. However, from Sarah’s reaction in verse 10 we see that he must be mocking Isaac. Indeed, the apostle Paul — writing under the inspiration of the Holy Spirit — tells us in the New Testament book of Galatians that Ishmael was persecuting the boy. In other words, it wasn’t that the older boy was having a bit of innocent fun. He wasn’t just messing around with his little half-brother. There was something malicious going on. And Sarah immediately pressed Abraham to send Hagar and her son away.

Well, Abraham was greatly distressed about this. Just look at verse 11: He was greatly distressed because it concerned his son. He didn’t really want to send Ishmael away. But God spoke to him and told him to do what Sarah wanted: he should send Hagar and Ishmael away, because his true heir was Isaac, and not Ishmael and all of God’s promises to Abraham would be fulfilled through Isaac; and the nation God promised to bring from Abraham would come from Isaac, and not from Ishmael and his descendants. And so we read the very moving story of how Abraham sent Hagar and Ishmael away, and the mother and her son wandered in the desert. And soon they used up all their water. And because the boy was dying of thirst, and perhaps the mother couldn’t stand to see it, she left him under a bush and went away from him, and began to sob. But — wonderfully — God heard the boy crying. And an angel of the Lord showed her a well. And their thirst was quenched and they were able to continue their journey. And, verse 20 tells us, God was with the boy as he grew up.

But then the scene changes. And from verse 22 we’re back with Abraham and this covenant he made with King Abimelech whom we met in chapter 20. They made this covenant, this treaty with one another, and the chapter ends with Abraham planting a tree beside the well that he had dug. And there, he called on the name of the Lord.

So, that’s a summary of what happens in this chapter. But what are we to learn from these events? What lessons can we draw from this chapter?

God’s word is true

Well, first of all, this chapter reminds us that God’s word is true. He is the God of truth and everything he says is true. And this is emphasised in particular in the first two verses. So look at verse 1:

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

Two times in the one verse, we’re told that God did what was said he would do. He said Sarah was going to have a child of her own in her old age, and that’s precisely what happened. The Lord was gracious to her, kind to her, just as he said he would. And the Lord enabled her to conceive and bear a child, just as he promised. Then 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.

Think back to chapter 18 and the story of how the three visitors arrived at Abraham’s tent. One of them was the Lord himself and the other two were angels. And while they were there, they asked about Sarah. And then the Lord said:

I will surely return to you about this time next year, and Sarah your wife will have a son.

Next year, you’ll have a son. And sure enough, just as the Lord had promised, the following year, Sarah gave birth to a son. Right at the beginning of this chapter, Moses who wrote these things, reminds us that God had kept his word. The Lord is the God of truth and everything he says is true.

And that means we must always believe his word. We must always believe his word even when what he has promised seems impossible to us. Isn’t that the case here? Back in chapter 18, when Sarah heard God’s promise that she would have a son next year, she laughed. And she laughed because she did not believe it. It seemed impossible to her. She was already an old woman. And she looked at her old, tired body and said to herself:

After I am worn out and my master is old, will I now have this pleasure?

She didn’t believe the word of the Lord. She didn’t believe this was possible. But the Lord said:

Is anything too hard for the Lord?

And, of course, the answer is no. No, nothing is too hard for the Lord. And therefore we ought to believe his word because nothing, nothing is too hard for him and whatever he has promised, he can do, and he can do everything that he has promised.

The whole of the Bible teaches us the same lesson. In the days of Moses, God promised that he would bring the Israelites out of Egypt. And even though the Pharaoh said they could not leave, the Lord kept his promise and brought them out. He promised that he would look after them in the wilderness. And even though it seemed impossible that they should have enough food to eat and water to drink in the wilderness, the Lord provided for them. He promised that he would bring them into the Promised Land. And even though the River Jordan stood in their way, and even though the city of Jericho was strong and well-protected, the Lord brought them through the river on dry ground and the Lord caused the walls of Jericho to collapse whenever they blew their trumpets and shouted. And, over the years, the Lord helped them to take the rest of the land. And even after their exile to Babylon, the Lord kept his promise to them and brought them back. And as the New Testament opens, the Lord promised another old man, Zechariah, that his wife would have a son, and sure enough, she gave birth to John the Baptiser. And the Lord promised Mary that she would have a son, and sure enough, though she was still a virgin, she gave birth to the Lord Jesus. And, of course, the Lord Jesus’s birth was the fulfilment of all of God’s promises to his people in the Old Testament, that he would send the Saviour into the world. The Lord is the God of truth and his word is always true. Therefore we ought to trust his word even when what he promises seems impossible or seems to make no sense to us. And so, we ought to trust his promise to take care of us and to help us everyday. And we ought to trust his promise to pardon all our sins. And we ought to trust his promise to build his church in his way.

We worry about what how we’ll manage everyday nd how we’ll make ends meet. We worry that our sins are too great and cannot be pardoned. And we worry that the people will never listen to the preaching of the gospel. But what has God said? That’s the important thing. That’s what we should be listening to and believing. Instead of listening to our worries and instead of believing what our fearful hearts say, we need to listen to God’s word and trust that he will do all that he has said he will do. The Lord is the God of truth and everything he says is true.

The Lord was gracious to Sarah as he had said. 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 always keeps his word. And therefore we ought to trust in him.

People and land

So, that’s my first point this evening. The second is to remind you of something we’ve notice before. Back in chapter 12, when God first appeared to Abraham, the Lord promised Abraham two things. First of all, he promised that Abraham would have so many descendants that a great nation would come from him. And secondly, he promised to give to Abraham and his descendants a land to live in. So, he promised Abraham a people and a land. And I’ve mentioned from time to time that God’s promises to Abraham are fulfilled in two ways. They are fulfilled in an earthly, ordinary and provisional way. But they are also fulfilled in a spiritual, greater and eternal way.

The promise to give Abraham a people was fulfilled in an earthly, ordinary and provisional way because from Abraham there came the Twelve Tribes of Israel and all the Jewish people. A great nation really did come from him.

And the promise to give Abraham a land was fulfilled in an earthly, ordinary and provisional way because the Lord eventually gave Abraham’s descendants the Promised Land of Canaan. In the days of Joshua they entered the Promised Land and it became their home.

Well, this chapter deals with both of these promises: God’s promise of a people; and God’s promise of a land. You see, the birth of Isaac was the first step towards fulfilling God’s promise to give Abraham a people. Isaac was the first descendant to come from Abraham and Sarah. And in due course, from Isaac there came Esau and Jacob. And from Jacob, whose other name was Israel, there came the Twelve Tribes of Israel and the whole Jewish nation. So, Isaac was, if you like, the first instalment. He was the first step along the way towards the fulfilment of God’s promise to Abraham to give him a people. Isaac was only one son, but he was the first of many.

And the tree which Abraham planted in Beersheba, which we read about in verse 33, was the first step towards the fulfilment of God’s promise to give Abraham a land. As one of the commentators puts it, it was a landmark of God’s grace and a pledge that Abraham would stay in the land. And we can imagine Abraham, as he planted it, and sat under its shade, thinking about God’s promise and how not only this tree, but all the land around it would belong to his descendants one day.

Isaac was only one son, but he was the first of many. And this was only one tree, but it was the first of many in what would become the land of Israel.

However, as I’ve said before, God’s promises to Abraham are fulfilled not only in an earthly, ordinary and provisional way, but also in a spiritual, greater and eternal way. God’s promise to give Abraham a people is fulfilled in a spiritual, greater and eternal way because Abraham is the father of every believer. According to the New Testament, everyone who shares the faith of Abraham is regarded as one of Abraham’s spiritual descendants. And so, the Lord’s promise to make Abraham into a great nation is fulfilled by the church of Jesus Christ which extends throughout the world.

And then, the promise to give Abraham a land is fulfilled in a spiritual, greater and eternal way in the new heavens and the earth earth which we read about in the last book of the Bible where all of God’s believing people will live for ever and ever.

So, the promise of a people was fulfilled in one way by the people of Israel, but it’s fulfilled in a greater way by the church of Jesus Christ. And the promise of a land was fulfilled in one way by the land of Israel but it’s fulfilled in a greater way by the Promised Land of Eternal Life.

And so, as we read this chapter, and read about the son who was born to Abraham and the tree which Abraham planted, we should remember and believe that God had something far, far better in mind when he made his promises to Abraham. And we ought to pray to the Lord to fulfil his promise to Abraham and to increase his people around the world and to bring us, at last, to our heavenly home. We ought to pray that more and more people around the world will be added to the church. And we ought to pray that the Lord will guard us and keep us so that in due course we will reach the Promised Land of Eternal life and be part of the new heavens and the new earth which will be the everlasting home for everyone who shares Abraham’s faith. As we read this chapter and read about the son who was born to Abraham and the tree which Abraham planted, we should pray for the complete fulfilment of God’s promise to Abraham of a people and a land, and we should pray for the increase of the church around the world and for Christ to come again when all of his people will come — in body and soul — into our eternal home.

Faith versus works

So, my first point is that God’s word is true and therefore we ought to trust his word. My second point is that the birth of Isaac and the planting of this tree were the first steps in the fulfilment of God’s promise to give Abraham a people and a land.

For my third point, I’m going to refer to what the Apostle Paul said about this chapter in his letter to the Galatians. In chapter 4 of Galatians, Paul refers to both Hagar and Sarah and to their sons, Ishmael and Isaac. And the apostle Paul — under the inspiration of the Holy Spirit — uses Genesis 21 to teach us about the gospel of Jesus Christ.

Paul was writing to the churches in Galatia because they had become confused about what the gospel really is. The gospel Paul had preached to them was that we are justified — that is, we are forgiven by God and made right with God — through faith in Jesus Christ who died for us and rose again. Through faith in Jesus Christ, our sins are pardoned, we receive the gift of the Holy Spirit and we’re given the hope of eternal life. However, some new teachers had come along after Paul had left, and they had confused the churches in Galatia. These new teachers taught that faith in Jesus Christ was not enough. Yes, we must believe in the Lord Jesus. But faith in Jesus Christ is not sufficient. We must go on and add something else to our faith. They were saying that whoever wanted to be saved needed to believe and they needed to be circumcised as well. And only if they added circumcision to their faith could they ever hope to be forgiven by God and receive the gift of eternal life. They said: We’re not saved by faith alone; we’re saved by faith plus circumcision.

Now, maybe you’re thinking:

Big deal. No-one insists on circumcision today. This is just an ancient problem.

But unfortunately it’s a problem which exists in every age, though it takes different forms. You see, it seems we can’t quite believe the good news that we’re reconciled to God through faith alone. It just seems too good to be true. It seems too easy. Too simple. Surely there must be something more to it? Surely God expects us to do something more before he will accept us? Believing in the Lord Jesus seems too easy. There must be something for me to do.

And so people are always saying that we need to add something to our faith. It’s not faith alone; it’s faith plus something else. In Paul’s day, it was faith plus circumcision. In other periods of history, it might be something else. But whatever it is, the principle is always the same: People say faith alone is not good enough and we must add to our faith before God will accept us. It’s always faith plus this. Or faith plus that. It’s always faith in Jesus Christ plus something that I have to do for myself. God has done his part; and we must do our part to add to what he has done for us.

And that’s what Paul is thinking about when he reaches Galatians 4:21 and when he starts to refer to the story of Hagar and Sarah from Genesis 21. In Galatians 4:21 Paul refers to people in the churches in Galatia who thought that God will only accept us if we believe in the Lord Jesus and keep the Old Testament laws about circumcision. To such people, Paul says:

What does the law say?

Well, he answers his own question in verse 22: The law contains the story of Abraham. And Abraham had two sons. One — Ishmael — was born to a slave woman — Hagar — and so this child was born into slavery. The other son — Isaac — was born to a free woman — Sarah — and so this child was born into freedom. Furthermore, Ishmael was born in the normal way. There was nothing unusual or supernatural about his birth. But Isaac’s birth was special: because he was born when his parents old and past the age for having children. Nevertheless, God promised them a child; and in due course, when the time was right, God kept his promise and Sarah, despite being well past the age for having children, was able to conceive and have a son in her old age.

So Ishmael was born in the normal way, but Isaac was born as the result of God’s promise. That’s what Paul tells us in verses 22 and 23 of Galatians 4.

And the point Paul is making is that these two mothers stand for two ways of thinking about our salvation. Hagar stands for Mount Sinai, Paul says. And he’s referring to the mountain where God gave to Moses the Ten Commandments and all the other laws. And what Paul means is that Hagar stands for all those people who are trying to earn their way into the presence of God by keeping the law or by doing something else. In other words, Hagar stands for the way of self-effort. If I try really hard, if I try really, really hard to do all that God has commanded, then God will accept me. That’s what Hagar stands for. She stands for all those who think that our salvation is down to us and what we do.

And that makes sense, doesn’t it? It makes sense because, when Abraham and Sarah doubted God’s promise to give them a child, they decided to work it out on their own and to give God a helping hand. They thought that God couldn’t give Abraham an heir without some help from them. And so, Hagar helped them to get a son for Abraham. And so Hagar stands for all those people who think that God needs a helping hand. He can’t save us on his own; he needs us to do our part as well.

But then Sarah’s son was born as a result of God’s promise. And therefore she stands for all those who realise that salvation is through faith alone in God’s promise. God has promised to deliver us from our sin and misery by his Son. And whoever relies on God’s promise, and believes in his Son, trusting in what Christ has done for us, without also trusting in what we have done ourselves, they become the children of God. ‘Now you, brothers’, Paul wrote, ‘like Isaac, are children of promise.’

And that makes sense, as well, doesn’t it? Sarah was well past the age for having children. There was no way she could ever hope to have a child without God’s intervention. But the Lord did as he promised, and he enabled her to do what she could not do on her own, and she gave birth to a son. And none of us can save ourselves. And so, we need to rely on God’s promise and to trust in Jesus Christ to save us. And whoever believes become members of God’s family.

Conclusion

Well, once we understand that we can contribute nothing to our salvation, but owe it all to God and to his promise, then we’ll realise that the Lord God deserves all the praise and the glory and the honour for our salvation. We did not add anything to our salvation, because we are saved not by what we have done, but by God who gave up his Son for our salvation.

Well, how do we know whether we’re relying on ourselves and our own hard work and effort? How do we know whether we’re resting on Christ and on God’s promise to forgive us? Well, what do we boast in? And what do we talk about? Are you the kind of person who is always talking about the things you have done? When you’re around other Christians, are you talking about yourself and the things you have done?

Do you remember the Lord’s parable of the Pharisee and the tax-collector who went up to the temple to pray? Well, are you like the Pharisee who prayed about himself and how he was so much better than the tax-collector? Or are you like the tax-collector who knew he had nothing to offer to God, but who simply confessed his sins and shortcomings and asked the Lord for mercy? Are you like him? Look at Sarah’s testimony in verse 6 of Genesis 21:

God has brought me laughter.

Is that your testimony? Not what you have done for God, but what God has done for you.