Christianity's Dangerous Idea: The Protestant Revolution—A History from the Sixteenth Century to the Twenty-First

Protestantism is dangerous. It is an explosive and ultimately uncontrollable force that can destabilize and undermine church and government. It can reject time-honored truths, traditions and institutions—including its own—and posit new ones in their place, only to repeat this process again and again. Protestantism is infinitely restless, constantly moving in many divergent directions at the same time. Like evolution, it possesses astonishing power to create highly adaptive religious organisms and equally astonishing power to destroy them if they fail to develop appropriately.

This is how Alister McGrath, professor of historical theology at the Univer sity of Oxford, depicts Protes tantism in Christianity’s Dangerous Idea. Why is Protestantism so dangerous? Because it is based on a dangerous idea: that the Bible is the main source of authority for the Christian religion and that all Christians have the right to interpret it for themselves. This conviction is the source not only of Protestantism’s vitality and flexibility, but also of its lack of fixedness and its innate tendency toward schism. McGrath makes much of the former without losing sight of the latter.

McGrath’s task is to offer an interpretive history of the whole of Protest antism that seeks to clarify its identity and its defining inner dynamics. A number of factors have moved him to write this book, including a desire to accommodate new research on both pre-Reformation and Reformation Christianity; a wish to provide a more fair-minded treatment of key Prot estant personalities; and especially a need to account for the seismic shifts that have taken place within modern Protestantism, most importantly the spectacular growth of Pentecostalism.

McGrath, who also holds an advanced degree in science, deals with his subject critically but also sympathetically, employing the metaphor of evolution to help explain the nature and growth of Protestantism. While he does not openly advocate for the superiority of Protestant Christianity over other forms of the faith, he clearly admires its creativity and adaptability, and he implies that Catholicism and Orthodoxy have much to learn from their coreligionists, at least on this score.

The book is divided into three parts, titled “Origination,” “Manifestation” and “Transformation.” Part one tells the story of the beginnings of Protestantism, when the dangerous idea that Christians can interpret the Bible for themselves was allegedly hatched by Luther and others. To my knowledge Luther never actually spoke of a right of individual interpretation of the Bible, as McGrath claims, although he certainly believed that ordinary lay consciences could be taken captive by the Word just as his had, and that no ecclesiastical intervention was required, only grace. Still, the result was the same: ordinary Christians could claim that they understood the Bible as well as or even better than their priests, for each Christian was a priest too—another dangerous idea (though the priesthood of all believers originally had more to do with the ability and responsibility to pray for and encourage other Christians, not with interpreting the Bible for oneself). Justification by faith was yet another dangerous idea, one that McGrath depicts as a novel reaction to a minority soteriology in the later Middle Ages, and one that was not accepted by all early Protestants.

McGrath also stresses that early Protestantism was not a single, unified, coherent movement; it was a movement of movements that was characterized by conflict, tension and flux from the start. The only thing the early Protestants shared was the dangerous idea. And they quickly learned just how dangerous it could be when they found themselves unable to reach consensus on important matters of doctrine. After examining the failure of Luther, Zwingli and others to resolve their differences on the Lord’s Supper, McGrath observes, “We see here the fundamental difficulty that the Reformation faced: the absence of any authoritative interpreter of scripture that could give rulings on contested matters of biblical interpretation.”

Protestants attempted to remedy this problem by constructing various interpretative authorities—Luther’s catechisms, Calvin’s Institutes, the marginalia of the Geneva Bible—but none could furnish truth claims that were accepted by all Protestants. Whatever external coherence early Protestants had was largely dependent on the presence of a defining other—Catholics in the early modern period and secularists in the later modern era. This need for an external source of self-definition became part of the core of Protestantism.

In part two McGrath moves on to consider several fundamental questions regarding the identity of Protestantism, especially its relationship to the Bible. Here he emphasizes Protestants’ need to return constantly to scripture to reevaluate current beliefs, practices and structure and make sure that they reflect as faithfully as possible the light of the gospel. In this sense, Protestantism is more a method of doing theology than a specific set of doctrines or practices. This method does not and cannot yield an ample supply of eternal verities, but Protestants believe that it does provide sufficient clarity on the vital matter of “things that are necessary to salvation,” which is the real concern behind their belief in the Bible’s perspicuity. McGrath notes that the Protestant method is not for those “who like everything to be rigorously and clearly defined,” but it does appeal to those who believe that the gospel must be creatively and continually reincarnated in its ever-changing surroundings.

McGrath’s primary concern in part three is to trace the astonishing growth of Pentecostalism in the 20th century and to show how it has transformed the face of Christianity, especially in the developing world, where the vast majority of Christians live today. For McGrath, Pentecostalism is the exception that proves the rule about the core identity of Protestantism. Even though many other Protestants have been uncomfortable with it, Pentecostalism is thoroughly Protestant: it has rejected traditions, structures and beliefs (in a few cases, even the Trinity) that it considers to be unbiblical, and it has evolved into a version of Christianity that is well suited to its environment and expresses suppressed or ignored themes in scripture, most notably the active presence of the Holy Spirit and God’s great concern for the marginalized. In Pentecostalism Luther’s priesthood of all believers has become Azusa Street’s prophethood of all believers.

McGrath makes no attempt to predict the future of Protestantism, although he is not anxious about its survival. It is in Protestantism’s very nature to innovate, adapt and reform—semper reforman dum—as it seeks to discover ever more of the divine truth that lives in God’s word.

It is curious and a little disturbing that McGrath gives scant attention to this concern for truth. However, at a pivotal moment in the book he does cite an interesting line from a Puritan sermon that places the pursuit of truth at the very center of the Protestant quest. The preacher John Robinson told those about to embark on the Mayflower that their experience in the New World would afford them new insights into the divine reality: “I am verily persuaded the Lord hath more truth yet to break forth out of His Holy Word.” McGrath takes this as a “fitting epigram to the entire Protestant engagement with the Bible.” Protestants as a whole believe that there is always more truth to be found in the word, which is why they adopted the dangerous idea in the first place.

It is true that the defining Pro testant idea is dangerous. But one can question whether McGrath has plumbed the full depths of its threat. The real danger is that when confronted with the competing Protestant truth claims about crucial matters of faith—including those that touch on salvation—theologically reflective Protestants may lose confidence in their ability to interpret or even trust scripture, and thus their ability to know God. Sebastian Franck saw this danger already in the 16th century and thus opted for a Spiritualism that sought to transcend all dogmatic claims about God—except Spiritualist ones, of course. Fortunately, most Protestants do not experience this complete loss of epistemic confidence, at least not on a permanent basis, which may be the reason McGrath avoids discussing the risk.

Some people view the Bible largely as a human artifact that contains important human wisdom about God but needs to be supplemented and corrected by more modern sources of wisdom. McGrath makes clear that such liberal Protestants are a small minority in the Protestant world. It seems that most—including McGrath, perhaps—continue to believe in the perspicuity of scripture. It is remarkable, after all, that the vast majority of Protestants agree with one another and with most non-Protestant Christians about the essentials of salvation—that is, that it comes only through Christ and requires grace and faith. But one wonders if this surprising agreement is not owing to another yet dangerous idea that was present in the primordial materials from which Protestantism burst forth and that thus became part of its genetic code: the importance of clinging to the ancient rule of faith. If this is the case, Catholicism did not simply motivate the construction of a unified Protestant front; it also provided Protestants with a certain immunity against the most destructive possibilities of their core idea.