Sola Or Nuda? Testing The Reformation’s Claim Of Authority

Recently, a Protestant friend introduced me to the conversion story of Chris Castaldo. Castaldo, who grew up Catholic, left the Church in his twenties and became a Reformed Evangelical Protestant. He now pastors New Covenant Church in Naperville, Illinois. My friend and I often discuss conversion. He sees me as an anomaly—an exception—while he views converts like Castaldo as the rule.

To better understand Castaldo’s journey, I read Journeys of Faith: Evangelicalism, Eastern Orthodoxy, Catholicism, and Anglicanism. In this book, converts explain why they left their original tradition for another. An expert from that tradition then challenges their reasoning, and the convert offers a final response. In Castaldo’s chapter (Chapter 7), Dr. Brad S. Gregory of the University of Notre Dame provides the critique (Chapter 8).

Among all the reasons Castaldo gives for leaving Catholicism, one stands out to Dr. Gregory: authority—especially the authority of Scripture. Protestants call the belief that Scripture serves as the ultimate authority in a believer’s life sola scriptura. While Protestants like my friend and Castaldo affirm Scripture as the ultimate authority, they also appeal to other authorities—creeds, confessions, and the Church Fathers—in a subordinate role. They argue that this position avoids interpretive individualism and does not collapse into nuda scriptura.

In his response, however, Dr. Gregory rejects that distinction. He argues that the line between sola scriptura and nuda scriptura collapses under scrutiny because no one can escape interpretive authority.

The Claim of Sola Scriptura

To discuss sola scriptura, we must first define our terms.

Sola Scriptura: Scripture is the only infallible authority for faith and practice. Other authorities (Tradition, councils) remain subordinate and corrigible.

Nuda Scriptura: Scripture is used apart from binding Tradition or authoritative interpretation, often resulting in interpretive individualism.

Tradition: Teachings and practices handed down in the Church, whether oral or written.

Those who hold to sola scriptura claim they avoid radical individualism by appealing to the early Church, creeds, and historical continuity. They argue that these subordinate authorities help interpret Scripture and preserve unity around “biblical truth.”

But do they actually fulfill that promise?

Gregory’s Critique – The Collapse Begins

Gregory’s central critique of sola scriptura targets what he sees as its circularity. Sola scriptura claims that all traditions must submit to the authority of Scripture. However, Scripture itself requires interpretation.

Below is Dr. Gregory’s argument in full from his response to Castaldo:

It is sometimes claimed that the advocates of sola scriptura differ from hermeneutical individualists who in effect champion nuda scriptura apart from any ecclesiastical tradition and do indeed foment an objectionable exegetical anarchy. Some Evangelicals seem to think that sola scriptura, whether among sixteenth-century Protestant reformers or today, yields or can yield a coherent affirmation of legitimate conciliar decrees and faithful opinions of the church fathers that link contemporary Evangelicals substantively and historically to the tradition of the early church. (For example, see Chris Castaldo’s essay in this volume.)

Unfortunately, such arguments are perfectly circular, relying as they must on one contested interpretation of the Bible among others for their evaluative criteria of legitimacy and fidelity. Reference to the biblically “faithful teaching” within the Church’s tradition both begs the question about the correct interpretation of the Bible and implicitly undermines the notion that Tradition has any independent authority apart from Scripture, thereby rendering sola scriptura and nuda scriptura indistinguishable. A particular biblical reading among many rivals has already been deemed the criterion according to which conciliar decrees, patristic statements, and any other sort of Christian expression will be judged. Choose a rival reading, and different decrees and statements become correlatively legitimate and faithful. (Just try it.)

Truth be told, Tradition has no independent authority for Evangelicals apart from the particular interpretation of Scripture that a given reader happens to favor, and so is nothing but a corollary of that individual preference. Thus, however it is supplementarily clothed with creedal statements, conciliar decrees, patristic ideas, doctrinal formulations, confessions of faith, and theologians’ opinions, sola scriptura always veils a preferential reading of nuda scriptura. In the end, they cannot be distinguished. Else what is the point of insisting on the Bible as its own self-interpreting authority in the first place?

In other words, one cannot identify “true Tradition” without first choosing an interpretation of Scripture. Once that choice occurs, sola scriptura no longer functions as an external authority. It instead operates through the interpreter’s judgment, effectively collapsing into nuda scriptura.

The Argument in Logical Form

For clarity, we can restate Gregory’s argument in syllogistic form:

If Tradition is only authoritative insofar as it agrees with Scripture,
And Scripture can only be accessed through competing interpretations,
Then Tradition is only authoritative insofar as it agrees with a chosen interpretation.

Conclusion:

Tradition has no independent authority and is reduced to individual judgment.

Why This Matters

Why does this matter? Because sola scriptura makes a hidden move. It presents Scripture as the ultimate authority. Yet Scripture requires interpretation. In practice, authority shifts to the interpreter.

This shift produces competing interpretations and, with them, competing “faithful traditions.” It also leaves no principled way to adjudicate disputes among interpreters. The result is fragmentation and doctrinal pluralism.

The claim that sola scriptura differs from nuda scriptura therefore collapses. Both rely on individual interpretive judgment. Each “tradition” becomes a corollary of interpretation, not an independent authority.

This creates a significant dilemma:

If two sincere Christians, both affirming sola scriptura, arrive at contradictory interpretations, what principled way determines which one is correct?

Anticipating the Objections

Some may raise the following objections to Dr. Gregory’s argument:

The Holy Spirit guides interpretation.
The Church has authority.
Gregory describes abuse, not true sola scriptura.

Each objection raises an important question:

Does the Holy Spirit produce contradictory conclusions?
Who determines when the Church is correct or in error?
What prevents the abuse in the first place?

Furthermore, Castaldo’s response to Dr. Gregory (Chapter 9) fails to address his central claim that no meaningful distinction exists between nuda and sola scriptura. Castaldo argues that all belief systems involve some circularity (which concedes the problem), that Scripture is sufficiently clear (perspicuous) (which does not eliminate disagreement), and that interpretation belongs to the whole Church rather than an elite authority (which merely relocates the issue). In the end, Castaldo acknowledges interpretive plurality but offers no principled way to adjudicate it, leaving Gregory’s conclusion intact: what appears as submission to Scripture alone ultimately functions as submission to a chosen interpretation of Scripture.

An Invitation to Debate

If any serious Protestant reading this believes he can resolve the nuda vs. sola scriptura problem, I invite him to do more than comment on this blog. Because of the importance of this issue, I recently created a Discord server dedicated to discussing it in a clear, respectful, and logical manner.

The #welcome channel explains the purpose of the server:

Welcome to the Nuda vs. Sola Scriptura Debate Group.
This server examines the coherence of sola scriptura as a theological principle. The central issue is epistemological: Can Scripture function as the sole infallible authority without collapsing into interpretive subjectivism? Or, stated differently, is there a meaningful distinction between sola scriptura and nuda scriptura in practice? Many claim sola scriptura avoids interpretive chaos. Others argue it inevitably produces it. We are here to test that claim—rigorously.

To join the discussion, use the link below:
https://discord.gg/u2K8BYJ9

I welcome participants who want to engage this topic seriously. This server is not for trolling or casual argument—it is for those willing to think carefully, argue clearly, and engage respectfully.

Your Final Thoughts…

To conclude, let me be perfectly clear: the question before us is not whether Scripture is authoritative. The question is whether Scripture can function as authority without an authoritative interpreter. If it cannot, then the debate rests not between Scripture and Tradition, but between competing claims to interpret Scripture.

I look forward to reading your thoughts on the Discord server.