Summary: Righteousness has always been by grace alone, even Abraham was justified by his faith apart from works
It might be good to stop for a moment and think again about what it was that occasioned this letter from Paul. Remember that he’s planning to visit Rome but has so far been prevented. But in the meantime he wants to make sure that the Christians in Rome have a sure foundation for their faith. He’s very much aware that the gospel he’s been preaching is opposed on various fronts, but most especially it’s been opposed by those who come from a Jewish background, both outside and inside the Church. His opponents have been trying hard to undermine him by repeatedly going back to the Jewish heritage of the Church. They would have argued that the Scriptures were the word of God, and so Christians should be obeying what those Scriptures taught. It was a very clever and subtle argument, even if their methods of stopping Paul weren’t so subtle at times.
You see, the argument they were using was that the Christian Faith sprang out of the Jewish faith; that therefore the Jewish law was still in force. After all, wasn’t Jesus a Jew? Didn’t he come from the line of David and before him from Abraham? And surely Abraham as the Father of the Jewish nation should be followed. And of course it was Abraham who was instructed by God to circumcise his son as a sign that he was part of the covenant people of God. Can you see how the argument must have gone?
Abraham’s righteousness: By works or by Faith
Well, Paul has just finished arguing that obeying the law will do no-one any good as far as earning eternal life is concerned, but he still needs to deal with this question, "What about Abraham and circumcision?" So that’s what he goes on to consider. He asks "What was it that Abraham discovered as far as salvation is concerned?"
Now this is an area where it’s very easy to get confused. You see Abraham did lots of things that showed that he believed God. He left his home in Haran and followed God to some unknown destination. He didn’t give up when it seemed impossible that he and Sarah might have a child. He was ready to sacrifice Isaac when God asked him to. And it would seem at a first glance that all these things he did were what earned him God’s good pleasure.
So Paul asks: "what does the scripture say?" Well, what does it say? "Abraham believed God, and it was reckoned to him as righteousness."
Now Paul quotes this verse from Gen 15 knowing full well that the Jewish teachers had used it in the past to show how Abraham’s action had merited the righteous verdict by God. So he quotes it for a good reason. He wants to clear up that misunderstanding. Belief in God’s promise doesn’t constitute good works. When God says he reckons it as righteousness the whole idea is that it’s not earned. It’s without merit. Look at the argument in v4.
If someone works for a wage, at the end of the day they receive their wage as a right. There’s no need to reckon it to them, they just get it because it’s theirs by right. The idea of something being ’reckoned to you’ seems to be like a funds transfer from one persons account to another. It’s not their money until it’s transferred. So God assigns to Abraham a righteousness that he didn’t have by himself purely on the grounds that Abraham believed him.