Diana Butler Bass wrote this interesting paragraph in A People’s History of Christianity: The Other Side of the Story:

Even though Protestants view the Reformation as a success, the events of the sixteenth century unleashed a host of problems with which Christians had to grapple. To say, for example, that the Word of God acted as spiritual and theological authority for life created problems: Whose interpretation of the word was correct? How could a believer adjudicate between conflicting view of scripture? What happened when those in authority contradicted each other? And even worse, when those authorities–all claiming to be Christian–persecuted or went to war with each other, what then? The Reformation eroded traditional sources of authority and unity in Europe, opening Christian communities to questions and concerns unimagined by the medieval church. As the questions provoked many different answers, they also provoked warfare. Catholic kings challenged Protestant princes over territorial claims, and those in authority–whether Protestant or Catholic–crushed heresy and heterodoxy within their own borders. (p. 213)

Alister McGrath has dedicated an entire book to answering a question like this one when he wrote Christianity’s Dangerous Idea: The Protestant Revolution from the Sixteenth to the Twenty-First Century. It is a question of hermeneutics, of the authority to interpret the Scriptures. It may be the most poignant criticism of Protestantism that we have splintered the church into pieces over various interpretations of nearly every next imaginable. Should we still consider the results of the Reformation a success?