I would begin by making clear to whom all the promises were made (only Jesus, the true Seed of Abraham, Gal. 3:16), and in whom they are all fulfilled (only Jesus, 2 Cor. 1:20); and then show that, if anyone is in Christ, he is counted as Abraham’s seed, and thus an heir of all the promises which were made to Christ (and thus, to all the promises God ever gave, period). Galatians 3:26-29 establishes that beyond cavil, and Ephesians 2:11-22, 3:6. Then, Rom. 4:12-16 teaches this point very clearly: the promise that Abraham should inherit Canaan is expanded, and now he inherits the entire world (Rom. 4:13); and so also is his seed expanded, so that he is the father of the circumcision who believe, and also the father of all of us who are not Jewish and yet have faith. He is the father of us all, and the land promise made to him is expanded and given to us all. For that, cf. also Christ’s words in Mat. 5:5; “Blessed are the meek, for they shall inherit the earth“.

If all that is not clear enough (and indeed, Rom. 4 adresses the specific question of the land promise so directly that it would be foolish to argue against it), then you could also point to Acts 15:14-17, as an example of a very clear OT passage predicting the restoration of the nation of Israel that is being fulfilled today through the conversion of the Gentiles.

I hope that gives you a little food for thought. One other thing, a friend of mine recently did a series of posts on this question, which I would encourage you to look at. Here is the conclusion, and you can follow the links at the top of each page backward, to get to the first article, if you’re interested:

It’s Roland again. How would you answer somebody who affirms that not all physical Israel are true Israel and that the Church is in fact the “spiritual” Israel; yet also claims that the N.T. does not change or reinterprit the physical promises made to National Israel? This person believes I am only half right in my interpretation and that his interpretation gives a “fuller” understanding of the bible which allows God to keep his physical promises to Israel and yet bring in gentiles to allow them to share in the “spiritual” blessings of Israel.

And thanks to you to, Christina D.!

Nathan

Not sure what you mean by “descendants…not his own children”. But the Hebrew word behind the typical English translation “descendants” is the singular “zerah” (“seed”). I would advise you to see Galatians 3:16, then 3:28-29 to see what the significance of that fact is. Also, about the barrenness of Sarah, see first Romans 4:18-22; and also, I will soon have a new “Images of the Savior” post out on the birth of Isaac (Lord willing), which will reflect upon the significance of Sarah’s barren womb. Feel free to consult that article in a few days.

Blessings in Christ,

Nathan

Feel free to ask questions/add observations anytime – working through issues at that sort of deeply thoughtful level is how we grow. I think this kind of interaction is profitable and doctrinally-maturing for both of us.

The basic point I was trying to make there is the same point that Paul later argues for in Romans 9:6-13: and that is, that the fulfillment of the promise made to Abraham could not have referred simply to Abraham’s physical offspring. Instead, the promise was fulfilled when God supernaturally gave life, in order to establish his oath. If the promise were purely physical, the Ishamelites would be just as qualified to claim it as the Jews; but it is manifest from the beginning that they were not the recipients of the promise. Therefore, a different principle was operative in the fulfillment of the promise from the beginning. Given that the different principle involved the supernatural impartation of life, the understanding that the promise is brought to reality in all who are miraculously given new life (that is, regenerated), is strongly suggested. Abraham would be the Father of many nations through the regenerative power of God, who would give life to persons from every nation, thus making them by faith children of Abraham, who likewise believed (see Galatians 3:7, 26-29). In Galatians 4:21-31, Paul makes the same basic point, asserting that the Jews who trusted that they belonged to God on the basis of externals (including physical descent from Abraham) were essentially the same as those born to Abraham by Hagar. But they were not the children of promise, and therefore not in fulfillment of the Abrahamic oath. So negatively, simply being physically descended from Abraham did not qualify as the fulfillment of the promise; and positively, even among those not physically descended from Abraham, the promise was able to be fulfilled – God is able to raise up children to Abraham from the very rocks (Matthew 3:9). The Jews should have understood from the case of Ishmael and Isaac that mere physical descent was not enough; and the difference was not in the fact that some were descended from Sarah and some from Hagar, but rather in the fact that some were supernaturally given miraculous life, in fulfillment of God’s promise, and some were not. When the Jews were trusting that they were children of Abraham because they were physically descended from Abraham and Sarah, they were making the same mistake as the Ishamelites – the mistake that the promise could be fulfilled naturally/biologically, and not according to the power of God.

Glad you found it useful. God bless in your series — it is a vital subject to be taught to the church.

Nathan

Thank you for your cogent and concise article. I have found it very helpful in putting together my series on the covenant for my church. peace

john mitchell

Just wanted to point that out as it was a challenge to me when first reading this great article.

Thanks,

Bob Hayton

On this my skilled sparing partner, we are agreed.