This promise is a bit more specific: First, God promises that He will multiply Abraham, that He will give him a lot of descendants. Secondly, God explicitly connects His promise with land.
Both the promise of land and what I call fecundity—that is, population—are natural outgrowths of the Genesis 12 promise that we looked at just a moment ago. In that promise, you will recall, God assures Abraham he will become "a great nation."
Now, we all know that great nations have lots of land, and that great nations have lots of people. So, in fact, this second promise is really just an embellishment, a restatement of the first one that we saw in Genesis 12. But, there is something much more beyond this, a point that we need to make, a dimension I need to mention in the Genesis 13 promise that we dare not miss. God says He will give this land to Abraham and to his descendants forever. We will come back to that idea in just a minute..
Let us see what we can do with all of these promises. I suggest to you that if we put all these promises together (the ones in Genesis 12, 13, 15, 17 and 22), we come up with a composite promise that has some common threads. Let us identify some of those common threads that appear in this promise. First, there is the eternal possession of land. That is obvious.
Secondly, a thread which to me is even more important is fecundity, or population. God promises Abraham, who had no son at all through Sarah during the time of the earlier promises, that he will be the ancestor of many peoples. No wonder Paul encapsulated it by stating that it was "the word of promise" as we saw in Romans 9:9: The "word of promise" was Isaac's birth to Sarah: "At this time I will come and Sarah will have a son."
Massive population appears to be (to me) the most conspicuous and the most ubiquitous thread of the promises. People! Lots and lots of people! They will need land, so God is going to give them land. He gives them land in perpetuity. But, land without people has about the same potential as the lunar landscape if you think about it. It does not do much good. People are what is going to be needed.
Let us take a look to see if I can back that statement up with a few specifics. We will look at five points. First, the promise of the eternal possession of land is really a promise of God's Kingdom. That promise is, as we saw in Genesis 13, to include all compass points—northward, southward, eastward, and westward. Further, the land is given over in perpetuity. It is given over forever. It will be secure, never to be snatched away by an enemy in, for instance, an act of war.
The four-compass-points promise is in fact a promise of the universe. That is how big the chunk of land that Abraham is going to receive.
We will not turn to Romans 4:13, but Paul speaks there of "the promise that He [Christ] would be heir of the world." In Revelation 21:7, Christ Himself states that "[H]e who overcomes shall inherit all things." I think the Greek means "the all, the everything."It is the universe.
Let us not forget, as well, in other scriptures (although we will focus mostly here on Genesis 13:15), that the promises involved land that will fall to Abraham as well as to his descendants. Not just to his descendants, but to Abraham himself. So this cannot just mean that Abraham's descendants, throughout their various generations over time, are going to receive the land and keep it. It does mean that. But God says that Abraham himself will inherit the land.
And yet in Acts 7:5, Stephen makes it clear that Abraham did not ever receive the land in his lifetime. No, not even enough to set his foot on. But even when Abraham had no child, God promised to give it to him for a possession and to his descendants afterward.
Abraham died without inheriting the land. To inherit it—to fulfill God's promise to him—Abraham is going to have to be resurrected. And, if he is going to receive it … . . .
But God's statement in Genesis 21:12 was plain, it was unambiguous. Your descendants will come through Isaac. It is a promise. It is a prophecy and God does not lie. He knew that from the character of the Being that he had always revered. His God does not lie. He does not say foolish things. He does not do jokes in that manner. He does not get people's hopes up and dash them. That is not how He works. Abraham's God is a faithful, truth-speaking God. So if He said your seed is going to come through Isaac, well then it was going to come through Isaac.
And this is how he came to a rational, logical conclusion. Isaac must live, he must live on, he must come back down the mountain if he were to have descendants as many as the stars of heaven and the dust of the earth—another divine promise which was said at least twice before in Genesis 13:16 and Genesis 15:5. He was not just looking for a couple of grandkids here. He was looking for thousands and hundreds of thousands and millions and billions of descendants.
He understood these divine promises were sure, that God had not lied to him. They would come to pass and so Isaac had to live. He had to be able, even if he did have to slay him, he would be resurrected because that promise still has to be performed. The prophecy has to be fulfilled and so Isaac would walk down the mountain with him. He knew that. God would resurrect him if it came to that. And this reasoning, this logical, rational thought process that he went through explains his confidence in telling his servants that he and Isaac would return.
It could only add up one way. You cannot throw in any kind of going back on things with God. He would not go back on His promise. That is not how God is. He is a faithful God. He would not do something evil, He would not lure him up there to kill his son. That is just not how God works. So he was confident that he had thought these things through in a way that came to a right conclusion. Perhaps his son was as good as dead in the next few hours, but he would receive him from the dead because God could not—COULD NOT—let him remain dead. The faithful God had promises to keep. And as I said before, he knew God would never renege on a promise. So he told his servants, we go to worship. We are going to go do as God has commanded. We are going to do His will, but we both will come back. Do not worry.
This is what Abraham believed, and this is what God is being faithful to in regard to us, in regard to salvation. It is His promise to Abraham. What we have here is the original promise.
That is the same promise, a little bit added to it, and God kept adding to it. Each time that He said it, He added a little bit more detail. He repeated it to Isaac, then to Jacob, adding more detail each time. Our calling to make us a part of Abraham's seed has already been fulfilled, and thus He has been faithful to the fathers—Abraham, Isaac, and Jacob—in that part of it. But now He must continue that faithfulness to them and add faithfulness to us by saving us; that is, by completing our salvation in order that the promise be completely fulfilled. This has to be done, because the promise made to Abraham, Isaac, and Jacob involves everlasting life.
The everlasting covenant part cannot be the Old Covenant, because it was never intended to be everlasting, and at this moment it is fading away, according to Hebrews 8:13. So there must be everlasting life to accommodate everlasting possession of the land. In Romans 11:26-29 He showed that the promise will be kept, and the salvation being spoken of there is the same salvation that we are involved in, except that it comes in the Millennium and the Great White Throne Judgment period. God is faithful, and He is thinking way ahead of time.
I am giving you these verses because I want you to see how confident God is that He can bring what He is saying to pass. In His mind's eye, in His mind, your salvation is already assured. It is His confidence in Himself to bring you into the land, and is a major cause for these things being written in the past tense, and in the perfect tense, because He is so confident that He can do it. He wants you to believe that, to carry with you that same kind of confidence in Him, in His faithfulness, so that you can live a life that is free from the kind of worries that we would normally have in leadership, because our leaders on earth normally do not fulfill their promises; but God does.
He adds to the dust—we have sand, stars which are considered to be countless. We see here strength, power, greatness in number. And not only that, those who come from Abraham are going to sit in strategic locations like doors and gates, letting people in and out.
That promise indicates that the nations that come from Abraham are going to spread over the whole earth. These promises either imply, or they clearly state large populations, large land surfaces, good geographical locations, good weather patterns, rich soil, mineral wealth, and enormous numbers of people. Do not these promises indicate that Israel is to become a major force in the world?
In the prophecies of the Old Testament pertaining to the end-time and beyond, Israel is almost always the subject of those prophecies, and other nations, regardless of how populous and powerful they are, are mentioned only as they come in contact with Israel. Here's Revelation, a book devoted almost exclusively to the end, yet evidence of Israel's existence is very sparse and vague. But at the time of the end, as it has approached, what has God done? He has revealed to His church where Israel is. The rest of the world doesn't give a hoot, but to the church it means something. It has been revealed so that we can make a proper use of this truth.
Indeed brethren, Israel is large, and it is important. Its combined population is somewhere around 500 million people. I should interject something here. The promises made to Abraham, to Isaac, and to Jacob are given in the sense of the entire completion of God's purpose, when all of mankind will be included within the sons of Abraham—all converted, all part of the family of God as well. We are in an important juncture of that, but in this time period—from the time Genesis 12 took place up until now, and in all of that history—God has been following through on all of His prophecies and promises regarding this.
Notice: Forever. I stressed earlier that Abraham understood that God’s promises to him were eternal, not a historical flash-in-the-pan for one generation, his own. That is why he did not want Isaac traipsing back to Mesopotamia. Stay away from that place.
This does not mean that Abram inherited the land at that moment. God clarifies through Stephen’s comments in Acts 7.
Significantly, by giving Isaac the same promises he gave Abraham, God gave both patriarchs the same prophetic vision. Paul, in Galatians 3:8, personifies the noun “Scripture,” saying that it, the Word of God, “preached the gospel to Abraham beforehand.” Paul then tells how it did that: Abraham heard the gospel through thepromises. Continuing in verse 8, Paul uses as an example the promise that all nations would receive blessings through Abraham. That blessing is most specifically a reference to the saving work of Christ, which would extend to the Gentiles.
So, both Abraham and Isaac heard the same gospel, the same promises. God inspired and motivated both men by means of the same prophetic vision. Of course, it is precisely the same prophetic vision—the same promises—that inspires and motivates us today. It is the gospel of the Kingdom of God.