Heresy: A History of Defending the Truth  seeks to explore many of these issues while providing a historical background for those looking into the topic.
“A heresy,” states McGrath, “is a doctrine that ultimately destroys, destabilizes, or distorts a mystery rather than preserving it… A heresy is a failed attempt at orthodoxy, whose fault lies not in its willingness to explore possibilities or press conceptual boundaries, but in its unwillingness to accept that it has in fact failed.”
One might wonder why McGrath utilizes this view of heresy, and it is important to see that his definition stands between two misunderstandings of the historical context of the development of heresy. McGrath argues that there are two positions about the history of heresy which are extremely popular but also highly anachronistic. The first is that heresy is something from outside of the church which was able to somehow “get into” the church and corrupt it; the second erroneous view is that “What determines whether a set of ideas is heretical or not is whether those ideas are approved and adopted by those who happen to be in power. Orthodoxy is simply the set of ideas that won out, heresies are losers.” Both positions suffer from an anachronistic view of the history of heresy and tend to over-emphasize certain aspects of that development.
The notion that heresy is some kind of “Trojan horse” smuggled into Christianity from without is historically untenable. Furthermore, this view generally holds that “Heresy was a later deviation from [the] original pure doctrine.” Instead, “heretics were insiders who threatened to subvert and disrupt [the church]….” However, the fact is that the notion of early Christianity holding to the best orthodoxy is a purely fictional historical concept. Rather, doctrine developed as new challenged were presented to the Christian faith or new truths were explored. Heresy was part of this development. Heresies were ideas that failed to take hold within Christianity because it was deemed to undermine the strength of the Christian faith as a whole.
Therefore, McGrath argues, it can be seen that the second view of the development of heresy is also historically mistaken. There was an orthodox core from which doctrine developed, and heresies were seen as defective. “The process of marginalization or neglect of these ‘lost Christianities’ generally has more to do with an emerging consensus within the church that they are inadequate than with any attempt to impose an unpopular orthodoxy on an unwilling body of believers.” Heresy was “an intellectually defective vision” of Christianity, rejected because it could not stand up to the theological challenges raised against it.
McGrath provides more development of the concept of heresy, and then turns from his analysis of the rise and rejection of heresy to a historical account of several early heresies. His analysis of these early heresies (ebionitism, docetism, valentinism, arianism, donatism, and pelagianism) provides significant historical support for his thesis that heresies are ultimately insufficient accounts of Christian theology and were rejected thereby. Against the thesis of Walter Bauer, who held that orthodoxy was an “ideological accident,” it is rather the case that “The relative weakness of institutional ecclesiastical structures at this time, including those at Rome, suggest that the quality of the ideas themselves played a significant role in their evaluation…”
It is also important to note that heresies are not necessarily tools aimed to destroy Christianity from within. McGrath is particularly concerned with the contextualization of heresies. These were often developed within a context of a question, like “What is the nature of Christ?” (Ebionitism). “The problem [of heresy] lay not with the motivations of [heretics], but rather with the outcomes of their voyages of theological exploration.”
McGrath ends Heresy with an exploration of the origins and development of heresy. Heresy, he argues, develops through 5 major strands, each of which usually involves turning theology towards: cultural norms, rational norms, social identity, religious accomodation, and ethical concerns (180ff). Heresies will continue to emerge as Christianity faces new challenges. Furthermore, orthodoxy is itself a process of ongoing development.
McGrath concludes with a vision for orthodoxy: “If Christ is indeed the ‘Lord of the Imagination’… the real challenge is for the churches to demonstrate that orthodoxy is imaginatively compelling, emotionally engaging, aesthetically enhancing, and personally liberating. We await this development with eager anticipation.”
Heresy is indeed something which has caught the popular imagination. McGrath’s book offers a reasonable, sound defense of Christian orthodoxy in an era wherein heresy is often portrayed as an unfairly suppressed system which should be resurrected. By providing a significant investigation of the historical background and development of heresy, McGrath avoids the two ahistorical extreme views of heresy: that it was entirely a plague from outside the church or that it was merely one of many competing ideas that happened to lose.
Christians would do well to have knowledge of the development of Christian doctrine. As more challenges are raised to the Christian faith, orthodoxy will have to continue to respond. Without a historical grounding firmly in place, Christianity is liable to change with the winds. Heresies repeat themselves, and Christians need to be ready to respond to these alterations of the faith. Heresies have historically been rejected not due to an internal power struggle, but rather due to their insufficient intellectual bases.
Alister McGrath’s Heresy: A History of Defending the Truth is one of those books Christians should have within reach on their shelf in order to readily access it as challenges arise. He provides an enormously useful historical evaluation of heresy which allows readers to avoid the pitfalls of ahistorical views. Furthermore, McGrath convincingly demonstrates the reasoning behind labeling a position as heretical follows from a corruption of Christianity which makes it less theologically or intellectaully viable. By providing Christians with a vision of orthodoxy and heresy that is both aware of its past and looking towards the future, McGrath has written an invaluable source.
Apologetics 315 Book Reviewer J.W. Wartick is a graduate student in Christian Apologetics at Biola University. His greatest interest is philosophy of religion--particularly arguments for the existence of God and the polemics against atheism. He frequently writes on these topics (and others) at http://jwwartick.com.
 Alister E. McGrath, Heresy: A History of Defending the Truth (HarperOne, 2010).