One of the great things about “the Mercersberg Theology,” was that it dealt with the tractarian movement in a way that addressed their concerns but defended the Reformation and vindicated justification by faith alone. In fact, in his The Principle of Protestantism, Philip Schaff articulated what Charles Hodge declared to be a “thoroughly evangelical” expositon of the doctrine of justification by faith alone. I agree with Peter Leithart when he writes,
Schaff’s book is not perfect. It is hard not to cringe when Schaff enthuses over German theology, and his affection for German idealism and Hegelianism is evident on the surface of the text. One wishes, moreover, that he had paid more careful attention to Puritanism, which he condemns as unhistorical and unchurchly.
Yet, the value of Schaff’s book goes far beyond its importance as a summary of the main thrust of the Reformation; its practical relevance for contemporary Protestants, especially Reformed Protestants, is incalculable. During the past several years, conservative Reformed churches have become increasingly polarized, and polarized precisely in regard to issues that Schaff’s book addresses.
On the one hand are those Reformed theologians and churches who appear to believe that the Reformed tradition has done and can do no wrong. All we need to address the doctrinal confusions of our day is a return to the Westminster Confession of Faith, and all we need to do to resolve liturgical chaos is to preserve a worship purer than Puritanism ever envisioned. To such, I recommend a prayerful read of chapter 3 of Schaff’s book, “The Diseases of Protestanism,”Efor the diseases that Schaff identifies are still plaguing us. And they are mortal.
On the other hand, some within the Reformed churches are all too aware of the diseases of Protestantism and conclude that, while there is no balm in Geneva, there is balm in Rome. For anyone facing this temptation, there is no inoculation quite like The Principle of Protestantism, for here Schaff, reflecting the concerns of his Mercersberg colleagues, especially John Williamson Nevin, presents a vision of a thoroughly catholic Protestantism that embraces tradition and that is not spooked by sacramentalism. Moreover, Schaff shows that this was the original Reformation vision. Few tasks are more pressing for the Reformed churches today than articulating and embodying that vision.