In Paul the situation is different. Paul has three main centers in his thinking, which make it not a circle but a triangle. The one is his eschatological consciousness, the certainty that in Christ eschatology is fulfilled and a New Reality has started. The second is the doctrine of the Spirit, which means for him that the Kingdom of God has appeared, that it is here, and there; that the New Being, in which we are, is given to us in Christ. The third point in Paul is the critical defense against legalism: justification by faith.

Luther took all three, of course. But the eschatological point was not really understood. He, in his weariness of the theological fights – you cannot become more tired of anything in the world than of theological controversies, if you always are living it; and even Melanchthon, when he came to death, one of his last words was: “God save me now from the rabies theologorum – from the wrath of the theologians! This is an expression you will understand if you will read the conf licts of the centuries. I just read with great pain, day and night, the doctor’s dissertation of a former pupil, Mr. Thompson, Dr. McNeill’s former assistant, an excellent work in which he describes in more than 300 narrow and large pages the struggle between Melanchthonism and Lutheranism. And if you read that and then see how simple the fundamental statement of Luther was, and how the rabies theologorum produced an almost unimaginable amount of theological disputations on points of which even half-learned theologians as myself would say that they are intolerable, they don’t mean anything any more – then you can see the difference between the prophetic mind and the fanatical theological mind.
Paul Tillich, A History Of Christian Thought – Table of Contents