"For a long time, as I was teaching the Bible at the seminary, I knew I had discovered something important, but I was never clear about just what it was. Then one day I was reading Romans 1:17 again: "Righteous people will live by faith." [It can also be translated: "People who are righteous by faith will live" i.e., not die as sinners."] That text helped me, for in the verse just before it were these words: "The Gospel is God's own righteousness. It is revealed through faith." So I connected the two: God's own righteousness [= the righteousness in God himself] and righteous people who have faith. When I made that connection, I saw what the Gospel was. The Gospel is the story of God's own righteousness. And what is that? Answer: The righteousness of God is God working to make us righteous. He makes us righteous when he leads us to put our faith in Christ."Before that discovery I had never noticed any difference between the righteousness of the law and the righteousness of the gospel. I always thought that Moses (the law) and Christ (the gospel) were basically the same thing. The only difference, I thought, was that Moses was farther back in history--and not God's full revelation, while Christ was closer to us in time--and God's 100% revelation. But I always thought that God's word from both of them was the same.
"But when I made this discovery that the righteousness of the law is one thing, and the righteousness of the gospel is something else, that was my breakthrough. [German: Da riss ich herdurch.]"