Frank Turk has made a reasonable request in the comments section of the previous post. He has asked for 200 words on why I believe that Abraham believed the expansive promises, and whether this is in tension with Christ’s statement that Abraham rejoiced to see His day. So here it is, in brief compass. Remember this is just the skeletal argument. It certainly needs to be fleshed out a good deal.
First, look at the content of the promises themselves in Genesis. In Genesis 12:3, Abraham is told, among a number of other glorious things, that “in thee shall all families of the earth be blessed.” In Genesis 15, he is told that his seed will be beyond numbering (Gen. 15:5.). This is precisely what Abraham believed (in the text) when his faith was credited to him as righteousness.
Second, this faith of Abraham’s in the promise is expressly called faith in the gospel, and Paul does this as he repeats the content of the promise.
“Even as Abraham believed God, and it was accounted to him for righteousness. Know ye therefore that they which are of faith, the same are the children of Abraham. And the Scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, ‘In thee shall all nations be blessed'” (Gal. 3:6-8, emphasis mine).
What comes out of God’s mouth when God preaches the gospel to Abraham? An expansive promise concerning the salvation of the world. And, as mentioned before, Paul settles this as talking about Abraham’s inheritance of the world (Rom. 4:13).
When Abraham believed this, he was looking for, among other things, a city with foundations, “whose maker and builder is God” (Heb. 11:10). And this is why Abraham when he saw the day of Christ, rejoiced to see it and was glad. He did not look forward to the first coming of Christ as the final fulfillment of the promise, but rather as the groundbreaking for the fulfillment of the promise. The cornerstone was laid, and this indicated that construction on the city had commenced. In a similar way, Abraham saw his Seed in the advent of Christ, and he rejoiced. But he will not see all his seed (who are what they are by virtue of their place in the Seed) until the last generation rolls in.
So, may our gracious God not only impute the righteousness of Christ to us because we receive His word the way that Abraham did (which we should certainly do), but also may He give us the faith to believe what Abraham did.