To return to the question about the identity of the descendants of Abraham as far as the unconditional covenant is concerned, it's all explained in Genesis 17:15-22, as we shall see.
Sarai too was blessed by a name change, though with it was a reminder that perhaps sleeping with Hagar wasn't going to be the way that God had in mind when He spoke of Abraham's offspring. Her name was changed to Sarah, with the words:
"I will bless her and will surely give you a son by her. I will bless her so that she will be the mother of nations; kings of peoples will come from her." (Genesis 17:16)
That made Abraham laugh so much he fell over. A child at the age of 100? And Sarah's 90 years old! He was troubled about Ishmael, now 13 years old. What was to happen to him? It was then that God made very clear His intentions.
Abraham was going to be the father of two distinct peoples. The first would be descended from Ishmael. He will found a dynasty of twelve rulers and he will be made into a great nation. But it would be the second people with whom God would establish his covenant.
"... your wife Sarah will bear you a son, and you will call him Isaac. I will establish my covenant with him as an everlasting covenant for his descendants after him." (Genesis 17:19)
The next year Sarah gave birth to Isaac, the one who is to inherit the blessings. What about Ishmael, then? Well God repeats what He said earlier about Ishmael's descendants being fruitful, but He also adds these words, in verse 21, 'but my covenant I will establish with Isaac ...' (my emphasis).
Again, couldn't be clearer.
We hear nothing of the boy until, a number of years later, God spoke again to Abraham.
"Then God said, "Take your son, your only son, Isaac, whom you love, and go to the region of Moriah. Sacrifice him there as a burnt offering on one of the mountains I will tell you about."" (Genesis 22:2)
It was to be a test. It was a test of Abraham's faith. Would God really destroy the very son, to whom God had earlier promised an everlasting covenant for his descendants after him? Abraham passed this test with flying colours, he even had the knife poised in his hand, ready to deal the fatal blow to his beloved son. God stopped him at the eleventh hour and again carved a notch on the faith-pole. Abraham showed the most amazing faith in God here, outweighing any lapses he may have made earlier in his eventful life. He was so sure of God's promises that he actually believed that God would raise Isaac from the dead, even though he had never witnessed such a deed before.
This is true faith and it is no wonder that Abraham became the father of a great dynasty.
"I will make you into a great nation and I will bless you; I will make your name great, and you will be a blessing. I will bless those who bless you, and whoever curses you I will curse; and all peoples on earth will be blessed through you." (Genesis 12:2-3)
It's tempting now to declare 'that's that', but it's not that simple, I'm afraid. It is now time to backtrack and examine the objections to the approach I have taken. My approach has been to look at the text just as it has been written, taking the meaning from a plain-reading of the text.
Others, though, would object to this approach, attacking it from two different angles.
Firstly, there are some specific objections to how the text has been interpreted.
Some would say that, despite what the literal reading seems to imply, there were conditions added to this covenant with Abraham, meaning that the descendants of Abraham could lose their rights to the land, by breaking certain conditions. To be frank, you have to bend your logic considerably to get a grip with these conditions.
They can be identified by considering the following questions. What would have happened if Abram hadn't made the journey to Canaan (Genesis 12:1)? What if his descendants didn't become a blessing to the nations (Genesis 12:2)? What if Abraham didn't 'walk before God' (Genesis 17:1)? Well, history tells us that he had, he did and he did and so any further discussion on this is pointless.
Others look at the promise of land given to Abraham, saying that surely this promise was fulfilled at the time of Joshua and so has no relevance to us today. This objection will be discussed a little later, when it is more relevant to do so.
(This is an abridged extract from Steve's book Outcast Nation)