We have just sung the hymn, Come Thou fount of every blessing. It was written by a man named Robert Robinson, who lived in the middle of the 18th century. In his 20's, when he wrote this hymn, he became minister of a Baptist church in Cambridge, in England. It was a ministry of great power – all Cambridge went to hear him preach. He began as one fully orthodox in doctrine – but then he was affected by 18th century rationalism and 'free thought'. He began to drift away from faith – and was only just kept from losing it altogether. Prone to wander is indeed his epitaph.

1. Sin in the human heart & the character of God's heart.

But Robinson is not unique. It is sin – as a principle of unbelief and disobedience – which remains in Christian hearts – that can make any one of us wander from the Lord. Not to mention Satan, who seeks always to destroy our credibility as Christians.

This new episode in the story of Abraham underlines this possibility for us all. For we see him repeat a sin that spoiled his walk with God 25 years previously, in Egypt.

But if sin in the human heart is one thing I want to speak about – the other is the character of God's heart – his grace and loving purpose. Abraham fails to trust God's promises. He deceives others and is cruel to his wife – but God is utterly faithful to Abraham and Sarah. In a dream God tells the truth to King Abimelech – and thereby brings about Sarah's rescue. It was at the cost of Abraham's humiliation – but, I'm sure, it also brought about Abraham's repentance.

Does it seem incredible to you that Abraham – after receiving the promise about Isaac's birth – after praying so boldly about the fate of Sodom and Gomorrah – should so shamefully succumb to the fear of man?

But God was teaching Abraham – and us – some very important lessons. The first of these is that sin – as a principle of autonomy and independence from God – and of defiance of God's will – remains in a believer's life as long as he remains alive in this body. All that a Christian does – continues to be tainted and affected by it – in his motives and in his performance. A true believer – one in whom God's Spirit dwells – desires to glorify God in his life. He therefore longs to be victorious over this indwelling sin.

2. Victory over sin only by God's grace and help.

As a result, we have a lifelong fight on our hands. How can we be victorious? Only by the grace of God and with his help. It was only by God's restraint within that Abimelech was kept from sinning. We cannot do it in our own strength, or by any outward coercion from a knowledge of what is right and wrong – from an external knowledge of God's law.

It was to convince Jews of the impotence of the Law (given through Moses) that Paul wrote, I do not do what I want, but I do the very thing I hate. Now, if I do what I do not want, I agree that the law is good. So then, it is no longer I that do it, but sin which dwells within me. For I know that nothing good dwells within me, that is, in my flesh. I can will what is right, but I cannot do it. (Rom 7:15-18 RSV)

Long before Paul, Jeremiah had, in effect said the same thing, The heart is deceitful above all things and beyond cure. (Jer 17:9) and the Lord had pointed him to the answer – I will make a new covenant with the house of Israel... I will put my law in their minds and write on their hearts. (Jer 31:31,33) The prophet Ezekiel was given the same promise, I will cleanse you from all your impurities... I will give you a new heart... And I will put my Spirit in you and move you .. to keep my laws. (Ezk 36:25-27)

This is the privilege of the Christian – the believer under the New Covenant – so that Paul can say, Live by the Spirit – and you will not gratify the desires of the sinful nature [the flesh]. (Gal 5:16) So our victory begins with our taking care that we don't fall (1 Cor 10:12) – by our recognizing our proneness to wander away – even after years of walking with God – even after tremendous spiritual experiences, as Abraham had done.

And victory is achieved only by relying on God's help, whenever we are tempted, and on his guidance day by day, because of the deceitfulness of our own hearts. The wonderful thing is that God – with undeserved love (for that is what grace is) – God comes again and again to our rescue. Nor does he let us go without rebuking us – if necessary through the mouth of a non-believer.

3. Our neighbour – and our thought-life.

That was the second thing God was teaching Abraham. Our neighbour may be more godly than Abraham – or we – give him credit for. He may hear God speaking to him, when we fail to – and he may well rebuke us about sins we have overlooked, or even those we are about to commit. [The most startling Biblical example of that, is Pharoah's unheeded warning to Josiah, which led to Josiah's death. (2 Chron 35:20-24)]

Abimelech knew something of God's holiness – for he knew of God's hatred of adultery. To commit adultery is not just an offence against our neighbour – it is an affront to God, and incurs his judgement, even if done in ignorance. But Abimelech now learned that God was just. For God acknowledged Abimelech's integrity – and was giving him a chance to put matters right.

Abimelech had other good qualities. He took responsibility for the welfare of his kingdom – by telling his dream to his officials, whom he treated as sharing his concern – and who would be his witnesses of his right dealing with Abraham. By their response, they showed they also respected and feared God. And wasn't Abimelech more thoughtful of Sarah's honour than Abraham was?

So Abraham learnt what God required. He hadn't got God's written law. He didn't know about the wonderful life and love of the Lord Jesus. He hadn't got any of the Bible. But we have. We should be reading it daily. We should meditate on the life of Jesus – and asking him to make us, by his Spirit, more like him. Because, you see, the battle is in our thought-life, first of all.

What was your reason for doing this? [NIV] What were you thinking of? [RSV] says Abimelech. I said to myself [NIV] I thought [RSV] says Abraham. It is clear that Abraham hadn't asked God to correct his thought-life. But have we?

Abraham says, in effect, that it was fear that again let him down. Sin attacks us where we have a weakness. Do you or I know where we are weak? Are we on our guard? Of course, that fear was sinful. It came from a failure to trust in God's promise to care for him, and to give him a family through Sarah. But Abraham was unable to see that. Sin blinds. (Matt 15:16; 23:16; John 9:40,41)

So Abraham and Sarah had agreed to say that they were brother and sister. Effectively this was a lie. And it put Abimelech and his officials in peril of God's judgement! And it all began when Abraham thought that Gerar was as godless as Sodom and Gomorrah! How mistaken he was – but how readily we pass judgement on others! What do we think about our neighbours and work colleagues?

Of course that lie also put Sarah's honour at risk – to say nothing of God's promise of a son by her. She had every right to Abraham's loving care and respect, but didn't get it. By making this a settled policy, Abraham had shut the door on putting into practice what he was learning about God's will and care. But then – perhaps we have things in our lives which we never discuss with our partners – or matters to do with our partners which we never discuss with God?!

Sin was affecting all Abraham's behaviour and relationships. Sin indwells – it attacks where we are weak – it blinds – and it makes us dumb. For it spoils and takes away our ability to give God the right place in our speech. Abraham speaks here like one worldly man to another, When God caused me to wander from my father's house.. (20:13 RSV) That could almost be rendered, When God led me astray..

Are you tempted, in the presence of non-Christians – as I have been – to explain your spiritual history in secular terms and phrases? Let's avoid doing so any more! Compare Abraham's words here with his testimony later [in chapter 24] The LORD, the God of heaven, brought me out of my father's household and my native land... spoke to me and promised me on oath, saying, 'To your offspring I will give this land'... (24:7)

4. God taught Abraham about himself, by allowing him to fail.

Now let us reflect on what God was teaching Abraham about himself. Once again, God was teaching Abraham that he, God, was in charge of events. I'm sure God knew what would happen when Abraham went to Gerar, which was near Gaza on the coastal plain.

Here Abraham was meeting a new people – the Philistines – who had probably come from the Aegean or Minoan Crete – then at the height of its power, and trading throughout the Mediterranean. A great influx of these poeople was to come 400 years later, at about the same time that Israel entered Canaan. But even in their earliest settlements, they seem to have been a people ready to use military force. God knew Abraham would be afraid and would resort to his usual stratagem. But he wanted Abraham to face up to the truth about himself, and to see that this way was sinful. So God allows Abimelech to take Sarah, but keeps him from touching her. Nothing is said this time about Sarah's beauty – she is 90! – but she was related to this powerful and prosperous sheik, who had just arrived on Abimelech's patch!

God wanted Abraham to realise his hatred of sin – and how it spoiled their friendship. It had to, because it had to do with disbelieving God's word, not trusting him, and not obeying him. When we sin, we are inevitably estranged from God. That is what we mean when we say God is holy – he can have nothing to do with it. Abraham knew that well enough, because he was aware of God's recent judgement on Sodom and Gomorrah. But Abraham needed to know – and so do we – that God is equally opposed to our sin – and he wants us to be opposed to it, as well.

God was also plainly teaching Abraham of his loving mercy and grace – to the undeserving. Abraham was undeserving – as we are, too – but God, because of his own character, and his pledged love, came to Abraham and Sarah's rescue. As God expressed it years later to Jeremiah, I have loved you with an everlasting love; therefore I have continued my faithfulness to you. (Jer 31:3 RSV)

At the same time God was revealing his loving mercy to those outside Abraham's family – outside of his covenant with Abraham. In this way he was reminding Abraham of God's purpose to bless all the world through Abraham and his offspring. We know that that was, above all, to be through Christ – through Jesus dying for us on the cross. Because of our sins, we deserve only judgement – but God, in his love and mercy, has made a way by which we may be forgiven. The Son of Man came... to give his life as a ransom for many. (Mark 10:45) You were ransomed... with the precious blood of Christ. (1 Pet 1:18,19 RSV)

So, right then, God was showing Abraham that he was at work in the hearts of men – in a place where Abraham least suspected it. So he required Abraham to pray for Abimelech and his family. Abimelech would know of God's love and forgiveness when he was healed, and his womenfolk were cured of their sterility and bore him children. Do we realise that God wants us to pray for our neighbours – that they may experience God's love and forgiveness, too? Of course, there is irony here. Abraham's prayer for Abimelech's women is answered – but his and Sarah's prayers for children had never yet been answered! But even when the answer to our prayers appears to be, No – it may in fact be, Not yet. For God had the timing in his own hands – and the next chapter tells us that God kept his word, and Isaac was duly born – when Abraham was one hundred years old.

5. The believer's difference lies in his relationship with God.

Also in the next chapter we read that – probably a year or so later – Abimelech and his general Phicol – come to Abraham to make a treaty of friendship with him. They recognise that Abraham has a special relationship with God, God is with you in everything you do. (21:22) There is a difference between a believer and a non-believer. It doesn't lie in moral superiority. Both are equally sinners – only kept from acts of sin by God's grace and power.

It lies in a relationship. The Christian has asked for – and received – God's forgiveness and God's friendship. He has been born again as a child of God, and been adopted into God's family, so that he may call God – Father. This is a tremendous privilege – totally undeserved. But that is what we are – and our lapses into sin do not destroy that relationship, only our communion with God – and that communion must be swiftly restored by repentance and seeking cleansing and forgiveness.

And, of course, that relationship carries with it the responsibility of becoming in character what God calls us to be – and already counts us as being! He calls us his children – and he longs that we become like him. In fact, he will ensure, by his Spirit dwelling in us, that we shall become like him!

Others should be seeing something of what God is like, when they see us. So we need to change. To have his truthfulness instead of our deceit and evasiveness. His peace and trust, instead of our fear and sinful scheming. His patience and love instead of our impatience and lack of tolerance. His concern for the integrity and well-being of others, instead of our selfish concern for our own safety and well-being. His purpose of love reaching out to those who know nothing about it – instead of our preoccupation with our own interests.

Living by faith is to have an assurance of our undeserved relationship with God. A relationship by grace – notwithstanding our sin and failure. It is to know we are loved, accepted, forgiven for Jesus' sake, not our own.

Living by faith – we live in that relationship as a child of God. In Christ Jesus our Lord.. and through faith in him, we may approach God with freedom and confidence.(Eph 3:12) As Jesus has said to us, My Father will give you whatever you ask in my name... Ask and you will receive, and your joy will be complete. (John 16:23,24)

What greater thing can we ask, than to change and become like our Saviour? He who did not spare his own Son, but gave him up for us all – how will he not also, along with him, graciously give us all things?.. For.. [nothing] in all creation will be able to separate us from the love of God, that is in Christ Jesus our Lord. (Rom 8:32,39)

                                                                                                     Amen.