Philip Schaff, the founder of church history in America, was widely celebrated in his later career. Soon after his arrival from Germany, however, his Principle of Protestantism (1845) was stiffly denounced for its favorable attitude toward Roman Catholicism, harsh critique of denominationalism, and theory of historical progress leading to a church that would be both Evangelical and Catholic. Charles Hodges review of the book provided the most cogent analysis of its implications for American Christianity. Schaff further clarified his understanding of progress in What Is Church History? (1846)...