Protestantism as a whole is founded on certain doctrinal assumptions which underly the entire Protestant system; these assumptions form a common basis from which various strands of Protestantism begin, and then branch out into a wide variety of different doctrinal traditions. Among these most basic Protestant doctrinal foundations stand two especially important pillars: the perspicuity of scripture, and sola scriptura. The perspicuity of scripture is the idea that the Bible is, at a basic level, understandable to the common Christian; it is clear enough that any well-intended Christian may come to it and upon serious and sincere inquiry into it, clearly understand at least the most basic doctrines of the Christians faith. While some things will be harder to understand, the basic gospel and rule of faith will be abundantly clear to anyone. Sola scriptura is the notion that we ought to generally base our understanding of Christian doctrine on practice on the Bible alone; other sources lack the reliability and authority the Bible has, and so, cannot be used as a basis for our Christian doctrine and practice.
The doctrine of the Trinity, however, is antithetical to both of these foundational Protestant doctrines. The doctrine of a triune God is said to be “the central mystery of Christianity” by its proponents; yet this is hardly compatible with the perspicuity of scripture for the central dogma of the Christian faith to be a mystery. Proponents of the trinity declare that ‘if one denies the trinity, they will lose their soul; it they try to understand it, they will lose their mind’. How, if the doctrine of the trinity in itself as a doctrine cannot be understood, can it be understood clearly from the Bible?
We must note that historic and creedal trinitarianism always declares that faith in the doctrine of the Trinity is required for salvation; that means that this cannot be dismissed as some tangental point of doctrine. According to the pseudo-athanasian creed, one who does not “so think” about the Trinity will be eternally damned to hell for his heresy. The doctrine of the trinity is, according to trinitarians, absolutely central and foundational to genuine Christianity. If that is so, then according to the perspicuity of scripture, the doctrine of the Trinity must be clear from the Bible- so clear that any well-intended reader would ascertain it from study of the Bible. It should be obvious that this is not the case at all, however. The doctrine of a tri-personal God is utterly absent from the Bible; so far from being a clear and unavoidable teaching of the Bible, it’s one that no one would even think of on the basis of the Bible alone- tradition is absolutely required to supply the ideas.
For evidence of this, one need look no farther than the early church. For the first couple of centuries, we have no record of any Christian asserting that the one God is tri-personal; not one. Assertions that Jesus literally pre-existed as a divine being, calling Jesus “God” etc, cannot be counted as a valid substitute for this, as Arianism would happily embrace such language as well. Indeed, most the early “proto-orthodox” writers are simply Arians of one shade or another, regarding Jesus as created by the Father, and being in some sense after the Father chronologically. Ancient assertions that Jesus is the “one God” on their own will not help either, when the reader sees that these confessions came from the lips of Sabellians, who denied that the Father, Son, and Spirit are distinct persons. If the doctrine of a triune God were clear from the Bible, how did the church miss this “clear” mystery for a few centuries? And how could the intense fourth and fifth century debates over the trinity and incarnation have ever occurred over such a clear mystery? How could at times the majority of bishops miss something so clear?
The very fact that the doctrine of the trinity is a “mystery” should make it plain that it is inherently contrary to the perspicuity of scripture. There is no such thing as a ‘clear mystery’- a ‘clear mystery’ is a contradiction in terms. Yet this contradiction is exactly what magisterial Protestantism has attempted to embrace by accepting both the mystery of the trinity and the perspicuity of scripture.
The doctrine of the Trinity is equally a problem for sola scriptura, for similar reasons. We have already addressed that the doctrine of the trinity is absent from the Bible, and that on the basis of church history alone, the honest trinitarian must admit that even if he thinks the doctrine is hiding somewhere in between the lines of the Bible, it at the very least is not clearly articulated in the Bible the way the perspicuity of scripture would demand that such a central and foundational doctrine must be.
Where then is the doctrine articulated clearly? Where must one go to discover the line between trinitarian orthodoxy and heresy? Not the Bible, certainly, but the rulings of councils and historic creeds. These creeds and conciliar rulings, however, are not part of the Bible, and yet are vital and necessary for ‘orthodox’ trinitarianism. This blatantly contradicts sola scriptura, though; how can a Protestant say that something outside the Bible is necessary for understanding basic and foundational Christianity? And not simply for understanding it, but for knowing where the lines between what is regarded as basic and foundational Christianity and damnable heresy lie?
It makes total sense that those who reject sola scriptura and appeal to councils, creeds, and popes as authorities alongside scripture can consistently regard Arianism and various deviations from creedal trinitarianism as heresy, and exclude these from their churches; but how can Protestants do this? The lines between heresy and orthodoxy on the basis of which they wish to exclude certain ‘heretical’ groups do not exist in the Bible; they can only be found outside the pages of scripture in tradition. Here we see the inconsistency- a Protestant cannot appeal to such tradition as having binding authority, and yet, must do precisely that to exclude trinitarian heresy. Only by the exclusion of such heresy can proper trinitarianism be maintained; and so, it will appear that tradition is utterly necessary to maintain the doctrine of the trinity in a church. Yet this is inconsistent for a Protestant, who has taken his stand on sola scriptura, and rejected the notion that ecclesiastical tradition holds any binding authority.
Consideration of these facts will show that it is unreasonable for anyone to attempt to be simultaneously Protestant and uphold creedal trinitarianism. One of these or the other must go, if a person will be consistent- and there is no virtue in inconsistency.
The suggestion of this author is to jettison trinitarianism. Sola scriptura and the perspicuity of scripture are both true, and aren’t the problem here. The problem is Protestants not acting consistently with these foundational principles by hanging onto teachings about God and Jesus that God has never revealed. To be Christian is, at a foundational level, to follow Christ Jesus, and so our understanding of Who God is and who Jesus is needs to match with, and be instructed by Jesus’s own teaching on the matter. The Bible is not unclear in teaching us to believe in one God, and one mediator between God and man, the man Jesus Christ; but until we are willing to actually base our beliefs on scripture, rather than the inventions of men, this will remain obscure for many professing Christians.