After reading This Post, much of the long and meandering comment thread that followed, a few follow-up posts, and taking-in all I could stand of the related videos, I was reminded again of This Outstanding Article and its final paragraph:

The assault on classic covenant theology of which Fuller has become a vociferous spokesman is being endorsed by some prominent leaders within even the broadly Reformed wing of evangelicalism. For example, in the foreword to Fuller’s The Unity of the Bible, John Piper, a popular lecturer at Reformed gatherings, tells us that “no book besides the Bible has had a greater influence on my life” than this one—an influence that has led him to dismiss covenant theology as not essential to a Reformed theology. It is imperative, therefore, that we who would maintain the Reformed faith recognize the Fuller theology for what it is: a radical renunciation of the Reformation, a subtle surrender to Rome. May we continue to cherish covenant theology, and in particular its precious doctrine of the righteousness secured for us by the active obedience of Christ. As Machen said: “No hope without it!”

*My emphasis

And I was reminded again of Kline’s greatness.

Kline knew.

***Update
Kline was still on to Piper two years later. Rube has shared this quote from Kline’s Kingdom Prologue lectures:

Piper is supposed to be a great Calvinistic preacher and so on, and he hates the idea of the covenant, and he hates the idea of works, and so he is destroying the gospel in the stuff that he writes, and whatever good things he is saying in some books it makes me cringe then when his books are urged upon people to read, because mixed in with them is this stuff which undercuts the gospel of saving grace, because he has no room for the idea of works, and that means there’s no room for the idea of Jesus’ works either, as the meritorious ground of your salvation.