What are the boundaries of orthodoxy?

What are the boundaries of theological orthodoxy in the Episcopal Church?

In the first chapter of the Holding Faith, Cynthia Rigby goes to some effort to emphasize that she believes there are times where we should take theology seriously and then there are times we should take theology with a grain of salt. We are not required, she argues, “to believe all theological ideas are equally profound, relevant, or life-giving. Faithful theological work includes discerning when God-talk is irrelevant and when it is, in fact, destructive” (xxiii). A few pages later she bluntly argues: “God calls us first and foremost to focus not on being ‘right,’ but on being faithful disciples” (xxv). This would seem to suggest that in her view, questions of orthodoxy are important, but of a secondary importance to how we treat each other in our day-to-day-lives.

On the other hand, the various authors of Heresies and How to Avoid Them repeatedly emphasize the importance of orthodoxy and ‘getting it right.’ Marcus Plested argues in Chapter 4: “We can never be entirely right in what we say about God, but we can certainly very easily be wrong. The concept of heresy remains essential for distinguishing between an incorrect and a correct (or at least less incorrect) articulation of the faith” (43). 

My sense is that a common answer would be “the boundaries of orthodoxy in the Episcopal Church are the Creeds as found in the Book of Common Prayer as interpreted by the early Councils of the Church (especially the first four).”  

While a seemingly simple answer, recent Episcopal bishops have held variety of differing perspectives on orthodoxy. For example, on one end of the spectrum we have a group of eight bishops who signed a joint statement in 2018 affirming their belief in the orthodoxy of exclusively heterosexual marriage. On the other end of the spectrum we find people like Bishop Spong who openly taught that the Resurrection was not a historical reality. Neither was (to my knowledge?) officially censored or defrocked for their public statements. 

This is an important question because Canon 4.1.h.2 says that members of the Episcopal clergy refrain from “holding and teaching publicly or privately, and advisedly, any Doctrine contrary to that held by the Church” or they are subject to ecclesiastical discipline.  

How wide or narrow is the scope, then, of what is considered to be the “Doctrine held by the Church”?

When does a difference of interpretation of the Creeds become heresy and who gets to decide? And why do they get to be the ones to decide?