Genesis 21 – Abraham: A great rift


GENESIS 21V1-21.



ILLUST: Who would have believed that it could happen? It seemed an impossible situation! To achieve such a result seemed extremely unlikely! Yet the facts speak for themselves! The South Africans beat Australia by 5 runs when Australia needed only 54 runs with 6 wickets in hand. Quite an amazing result.


We are always amazed when the unexpected happens!


ILLUST: Who would have thought that the tribes men who murdered 5 missionaries in the jungles of Ecuador would in the years to come would become Christians themselves. Through the witness of the wives of some of the men killed. BUT it is true.


Totally unexpected, but amazingly true.




With the birth of Isaac to Abraham and Sarah we are not just talking about the unexpected we are talking about the impossible. Abraham was 100 and Sarah was 90!! – it was physically impossible for them to have children. But here at last they have a son!!

Imagine the talk around the camp and even amongst the neighbouring tribes – Maybe Abraham and Sarah had told them what God had promised. “Can you believe it!! Old Sarah has a baby?”

And she [Sarah] added, “Who would have said

to Abraham that Sarah would nurse children” [v7]

God had kept his promises!!  Some 25 years had gone by since Abraham had left Ur and during these years he had received promises from the Lord.

God would bless him — he would have children like the dust of the earth — BUT Abraham remained childless — “Shall Eliezer of Damascus be my heir?? ‘No, one born in your house will be your heir'”  Still no child came then Sarah and Abraham took matters into their own hands. And Sarah gave her maidservant, Hagar, to Abraham to have a child by her [ this was an accepted practice of the time]. But still God said that it would not be Ishmael but one born from Sarah’s own womb. But 13 more years would pass before Isaac was born.

But now we read in 21v1.

Now the Lord was gracious to Sarah as he had said,

and the Lord did for Sarah what he had promised


God is faithful – he always keeps his promises. The birth of Isaac is proof of this fact.

If it were not true that God keeps his promises where would that leave us. Could we trust a God who broke his promises. If God broke his word where would our hope be? Where would our assurance be??

Our salvation is as a result of God’s promise.

“to as many as received him [Jesus]

he [God] gave the right to become children of God [Jn 1]

“If we confess our sins he is faithful and just

and will forgive us our sins

and cleanse us from all unrighteousness [1 Jn 1v9]


God’s promises are sure because he is faithful.

“… faith and knowledge resting on the hope of eternal life,

which God, who does not lie, promised before the beginning of time,

and at his appointed season brought his word to light…”

In our day and age we are very sceptical of promises and guarantees.

ILLUST: How do you view the sales pitch of the double-glazing Co. or the car salesman. Is this genuine or are we being ripped off??


God is not like that and Abraham knew it.


By Faith Abraham, even though he was past age –

and Sarah herself was barren –

was enabled to become a father because he considered

Him faithful who had made the promise.[Heb.11v11]


Abraham believed God and never doubted him for a minute!?? Is that true? NO!

Abraham’s faith was up and down – he believed and then he didn’t, and then he did and then he didn’t.

You see the waiting time for the fulfillment of God’s promises is not a waste of time. During the waiting God is testing and developing our faith. Yes, there are ups and downs; periods of doubt and disbelief. But all the time God is preparing us for the time when he will fulfill his promises.

“Sarah became pregnant and bore a son to Abraham in his old age,

at the very time God had promised him” [21v2]


From God’s perspective there was no delay. Isaac was born at just the right time; God is never too early or too late.

From Abraham’s perspective, though, it would seem that God had been dilly-dallying. Why hadn’t God acted sooner?  We only see our little patch, but God sees the whole picture and he knows what we need and when we need it and he always keeps his promises and fufills them at just the right time.



Abraham and Sarah were ecstatic! They called their baby ISAAC which means “Laughter”. The name given to them by God. When God announced that they would have a son Sarah laughed with scorn. Now they were laughing with Joy.



When Isaac was wean, probably about the age of three, Abraham threw a party. It was a great day for everyone. Everyone except Ishmael!!

Ishmael was probably about 16 -17 years of age by this time. For all this time he was the one and only son of Abraham and had enjoyed his father’s love. He no doubt expected to be the heir of all that his father had. But now this little baby had displaced him. The spotlight had moved to Isaac.

During the celebration Sarah looked across the crowd and saw Ishmael [the rebel teenager]  mocking Isaac. And all those old feelings of resentment and anger welled up inside her.  In anger she goes to Abraham, probably after the party when the were alone. And she looks him in the eyeballs and says “Get rid of that slave woman and her son

Abraham’s delight turns to distress. Surely this can’t be so?  Ishmael wasn’t in God’s plan; Abraham knew that but he loved Ishmael. He had rasied him for 17 years. Abraham consults God. And God tells Abraham what every Husband doesn’t want to hear “Do what your wife tells you to do.”

Ishmael must go. God promises to look after him but he must go.


What is God doing? Well he is setting the stage for an illustration  of a most significant truth.


BACKGROUND to Gal.4. Heretics  in the Galatians Churches- Judaizers.  Belivers from a Jewish background who had come to believe that salvation was by faith in Christ plus the adherence to certain OT laws, esp. circumcision.

They were coming to those who had come from paganism to faith in Christ and were saying, “You haven’t been saved, it is all very well to believe in Christ but you must also be circumcised” In other words it is not just faith in Christ but it is Faith plus this and this and this. Faith plus works. Paul attacks this teaching here and in other places in the NT because it was a wide spread heresy  and it is still with us today.

It is too easy to just believe surely I have to do something!!


READ Gal. 4v21-25.


Jewish nation receieved the law at Mt. Sinai and in time began to think that by keeping this law they could be saved. Not only had they taken the Law of God but they had added all kinds of other laws to it. Jerusalem [Jewish nation] had become bound up in legalism in trying to keep all these laws.


READ Gal. 4v25 – 31.





1. Son of the slave woman

2. Born in the normal way

3. Representative of the Old Covenant – Sinai-

earthly Jerusalem – centre of Legalistic Judaism.

4. Salvation by works.

5. Leads to slavery – In bondage, always striving, always trying to be accepted by God but never can be.

6. Persecutor.




1. Son of the free woman

2. Born as a result of promise – supernaturally

3. Represenative of the New Covenant – the Jerusalem that is above.


4. Salvation by faith.

5. Freedom – “If the son {Jesus} shall set you free then you are truly free”


6. Persecuted



There is something about the teaching of salvation by works that reaccts to the doctrine of salvation by faith. People get angry when you tell them that their is no other way to salvation except by believing in the Lord Jesus Christ.

READ  Gal.4v29 Again


At that time the son born in the ordinary way

persecuted the son born by the power of the Spirit.

It is the same now!

But what does the scripture say?

“Get rid of the slave woman and her son,

for the slave woman’s son will never share in the inheritance

with the free woman’s son” [Gal.4v29-30]


NO compatibility between legalism and faith. Before you can be saved you have to accept that there is nothing you can do to save yourself. It is all of God.


ILLUST: Contrast – the good person – the DIY salvationist AND the bad guy who cries to God for salvation with his dying breath. Which one will be saved?

The one who depends totally on God.


God waited until there was nothing that Abraham and Sarah could do. They were utterly helpless. Then God gave them Isaac.

Ishmael was simply the result of two people coming together in sexual union. Isaac was as a result of a miracle of God. Salvation is miraculous new birth – it is not the result of you working, or striving to improve yourself in order to make yourself more acceptable to God.

This whole incident illustrates the central truth of Christianity. Salvation by faith in Christ apart from works.




“Early the next morning”

Abraham obey immediately – it is not always easy to know exactly what God want. But when he has made it clear then we must obey right away. When we don’t it is always to our cost and often at the cost of others.

Single parents and needy teenagers are not new. Here was Hagar cast out with her teenage son Ishmael. But they were not alone – God heard their cries and in his kindness and mercy he cared for them as he had promised Abraham he would.

Hagar’s life had been full of trouble but the thing we need to notice is that the trouble in her life had not been of her own making. She was a slave girl whom Abraham acquired when in went down to Egypt in a period of disobedience. She was given to Abraham by Sarah so that they could have a child – again Abraham’s and Sarah’s disobedience and lack of faith. Now she was being sent away  with her teenage son.

Hagar and Ishmael were hurt by others – they were the victims of the sins and disobedience of others.

God’s care of Ishmael and Hagar is proof of his kindness to those people who are victims of the sins of others. There are many who suffer because of the sins of others.


ILLUST: Children – misused and abused. Wives whose husband’s have walked out on them. Emplyees whose bosses have mistreared them.


The message to those who have suffered because of the sins of others is, God cares.

There in the desert Hagar and Ishmael cried out to God and God heard and came near and He was with them. God made Ishmael into a great nation. God didn’t fix everything up! There are certain circumstances of life that just don’t get fixed but He was with them and showed them his infinite kindness.

If you are suffering because of the sins of others, know this, GOD CARES.


The birth of Isaac shows God keeps his promises.

The separation of Ishmael illustrates God’s rejection of salvation by works.

His care of Hagar and Ishmael shows God’s infinite kindness.


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