Over at Called to Communion, Tom Riello writes on The Doctrinal Seed of Scripture:

Doctrine is borne out of the Church’s life, her reflection and her experience. The doctrine of the Trinity, for example, was not so much a doctrine that was “proved” as it was experienced within the life of the Church. To be sure, the experience of the Trinity conformed to the teaching on the Trinity, but the teaching of the Trinity was also informed by the experience of the Church. The following quotation from the well-known and respected Church historian, Jaroslav Pelikan, demonstrates just how doctrine and practice developed and are being developed in the life of the Church. In this quotation, Pelikan makes the point that when you, especially as a Protestant, embrace the homoousion of Nicaea, how and where do you draw the line on doctrinal development? Once you accept Nicaea, or for that matter, the canon of Scripture have you not conceded too much to the authority of the Church? Many conservative Evangelicals (e.g. the founders of the OPC and PCA) are frustrated by the liberals and their propensity to deny “orthodox” doctrine, thus, in the opinion of many Evangelicals the liberals are heretics. Yet, it must be stressed, the liberals are only being consistent. You see, once you have deconstructed Ecclesiastical authority, it is darn near impossible to call something or charge someone with heresy. “Heresy according to whom?” is the liberal response to the Evangelical. Let’s now read the quotation from Pelikan:

The New Testament, certainly no less than the Old, has continually taken on new meanings in the course of the history of its interpretation, meanings that have sometimes been the consequence of what it did not say as much as of what it did. For to both Testaments we may apply the sage comment of a scholar of the Hebrew Bible who has illumined some special chapters in the history of its interpretation. “Just as a pearl results from a stimulus in the shell of a mollusk,” Louis Ginzberg observed, “so also a legend may arise from an irritant in the scripture.” Whether as stimulus or irritant or inspiration, Scripture has dominated attention to the Virgin Mary though it has not always controlled it. . . . For biblical scholarship, the fact that “in the course of centuries Mariology has had an enormous development” may be something of a problem. But for historical scholarship, that development is also an enormous resource. To be sure, Mariology was not the only doctrine to have undergone such a development; in fact, it would be impossible to identify a doctrine that has not done so. The most decisive instance of the development of doctrine, and the one by which the fundamental issues of what could by now be called “the doctrine of development” have been defined, is the dogma of the Trinity. For the doctrine of the Trinity was not as such a teaching of the New Testament, but it emerged from the life and worship, the reflection and controversy, of the church as, in the judgment of Christian orthodoxy, the only way the church could be faithful to the teaching of the New Testament. It did so after centuries of study and speculation, during which many solutions to the dilemma of the Three and the One had surfaced, each with some passage or theme of Scripture to commend it. The final normative formulation of the dogma of the Trinity by the first ecumenical council of the church, held at Nicaea in 325, took as its basic outline the biblical outline of the so-called great commission of Christ to the disciples just before his ascension. . . But into the framework of that New Testament formula the Nicene Creed had packed many other biblical motifs, as well as the portentous and non-biblical technical term for which it became known. . . . “one in being with the Father [homoousios toi patri].” With characteristic acuity, therefore, John Courtney Murray once formulated the implications of this for the ecumenical situation: “I consider that the parting of the ways between the two Christian communities takes place on the issue of the development of doctrine. . . . I do not think that the first ecumenical question is, what think ye of the Church? Or even, what think ye of Christ? The dialogue would rise out of the current confusion if the first question raised were, what think ye of the Nicene homoousion?” If the Protestant churches acknowledged the validity of the development of doctrine when it moved from the great commission of the Gospel of Matthew to produce the Nicene Creed, as all of the mainline Protestant churches did and do, on what grounds could they reject development as it had moved from other lapidary passages of the Bible to lead to other doctrines?. . . . To reject this development of doctrine on the argument that it was a development and that development was in itself unacceptable made it difficult for the biblical exegesis of the Reformation and post-Reformation periods to contend with those on the left wing of the Reformation…For having thus developed out of Scripture, the trinitarian perspective had in turn become a way- or, rather, the way- of interpreting Scripture. As it was systematized at least for the West chiefly by Augustine, this method of biblical exegesis was cast in the form of a “canonical rule [canonica regula].” The several passages of the Bible that appeared directly to substantiate the dogma of the Trinity, such as above all the baptismal formula the close of the Gospel according to Matthew and the prologue about the divinity of the Logos at the opening of the Gospel according to John, mutually reinforced each other to form the biblical proof for church doctrine. Conversely, however, any passage that, taken as they stood, appeared to contradict church teaching were subject to the “canonical rule” and required careful handling. When several chapters after the solemn prologue, “And the Word was God,” the Gospel of John had Jesus say of himself, “My Father is greater than I,” Augustine had to bring his heaviest weapons into action. If the Protestant Reformers and their descendants were willing to hold still for such a manipulation of the New Testament passages in the interest of upholding a doctrinal development that had come only in later centuries- and they were- what stood in the way of such manipulation when the passage in question was “This is my body” or “Thou art Peter, and upon this rock I will build my church?” (Mary Through The Centuries pgs. 7-11).

Once one acknowledges the sort of development Riello and Pelikan describe, there follows the need of an authoritative institutional caretaker for that development.