Taking his cue from my recent article at First Things, Rod Dreher asks a most reasonable question: what is orthodox Protestantism?

The problem with defining the term is that orthodox Protestantism is, in one sense, an abstraction. It correlates with no single institution. Thus, the Roman Catholic is here at an advantage, at least in theory: orthodox Catholicism is what the Roman Catholic Church upholds as true and practices in her worship. The unity of the institution makes the question straightforward. As there is no single orthodox Protestant church, the question is inevitably more challenging.

The way I was using the term in the article was with reference to the points of consensus of the Protestant confessions of the sixteenth and seventeenth centuries. Thus, when one compares, say, the Lutheran Book of Concord with the various Reformed confessions, significant points of agreement emerge: on the Trinity, on the Incarnation, on the uniqueness and sufficiency of Christ for salvation. We might summarize this as agreement upon the creedal faith of the early church, refracted through the debates over sacraments, salvation, and ecclesiology in the Reformation. Significant points of antithesis do exist within Reformation Protestantism, particularly on the Lord’s Supper as a point of division between Lutherans and Reformed, but aside from this significant issue, there is a high degree of fundamental commonality.

When one looks specifically at the Reformed confessions, the consensus is even stronger. E.F.K. Müller’s collection of Reformed confessional documents, Die Bekenntnisschriften der reformierte Kirche, is fascinating in this regard: the documents are drawn from across Europe and represent the productions of churches in a wide variety of linguistic, political, and cultural contexts. Yet there is substantial unity on all major topics. From the doctrine of God through the Incarnation to grace, justification, the word of God, the church, sacraments, and the afterlife, a clear core of orthodox Protestant teaching is there, despite the diversity of contexts–a diversity arguably much greater than that represented by the bespoke diversities of today, given the lack of information technology, easy and efficient transportation, and pop cultural unity in the sixteenth century (no international Manchester United Supporters’ Club in Luther’s day), things that are now a commonplace in our globalized world.

Catholics will no doubt respond that I am offering a false unity here. I have chosen those texts that reflect the core of Christian belief I myself prefer and, by privileging them as normative, have granted Protestant orthodoxy a coherence that it did not possess then and does not possess now.

This is not a trivial objection and certainly Catholic emphasis on the need for institutional unity as the foundation for recognizing doctrinal unity is a serious one. When Christ prays that his people would be one (Jn. 17:11), the Protestant tendency is to reduce this to a unity of doctrine and then to use this as a way of sidestepping the question of institutional unity. That impoverishes Christ’s intention here. Institutional unity is important as a witness to the truth. I for one do think it ridiculous that in the USA alone there are numerous presbyterian denominations who hold substantially the same doctrinal position but exist as separate institutional bodies. Yet even so, the problem of defining Protestant orthodoxy is not simply a Protestant problem.

If we recast the question as ‘What is Christian orthodoxy?’ it soon becomes clear that the problem is shared by Catholics and Orthodox too. This is because we live in a world of religious pluralism and that means we all live in a world of religious choice. Critics may say that I choose Reformed orthodoxy as normative for Christianity, but I can respond with precisely the same criticism of my Catholic and Orthodox friends. They too choose. They choose to prioritize historic institutional unity and continuity and make that the basis for their definition of what is the core of orthodox Christianity. That certainly addresses the concern Jesus has for something more than a notional unity based upon mere doctrinal agreement in the midst of institutional chaos but it misses that other important aspect of New Testament unity–that divisiveness is a function of doctrinal deviation (Rom. 16:17). The approach of ‘my institution, right or wrong’ over doctrine is as problematic in its own way as the Protestant tendency to ignore the challenge that our institutional fragmentation poses for our claims of doctrinal unity. It is why there have been Catholics such as Hans Küng whose teaching was acknowledged by his own church as highly problematic but who remained a priest in good standing. Institution trumps dogma in actual practice, even as this will no doubt be denied in theory.

And no one can avoid this problem of choice. I choose the Reformed confessions, Catholics choose institutional unity focused on Rome. Even cradle Catholics choose to remain Catholic despite the range of other options out there. As the great rock philosopher Geddy Lee expresses it in Rush’s “Free Will”: “If you choose not to decide you still have made a choice.”

So I return to my basic definition: Protestant orthodoxy is reflected in the consensus of the Reformed confessions of the sixteenth and seventeenth centuries. My choice. And they seem to cohere with what the Bible itself teaches. This does not solve all of the problems but, as I repeatedly tell my students, there is a sense in which Christian orthodoxy is the net result of all the problems one can live with as opposed to those one cannot live with. And for me, the fragmentary nature of Protestantism is less of a problem–though still a real, pungent problem–than the way in which institutional unity in Catholicism seems to relativize the relationship between belonging to the Church and actually believing what the Church teaches.

Carl Trueman is a professor of biblical and religious studies at Grove City College and a fellow at the Ethics and Public Policy Center.