I find this a very useful discussion even when I disagree on what is essential. For example, while Patton states that he is writing about doctrine, and that another post could be written on essential practice, I would suggest that whether or not the primary essential of salvation is belief in doctrines or certain practices, a combination of the same, or indeed none of the above, is itself a rather important doctrinal question. And since the question is on just what, doctrine and/or practice, is essential for salvation, it is doubtless an essential question, at least.
I use a different method of dividing these issues in my post Unity, Diversity, and Confusion. There I am not trying to state what beliefs are necessary for salvation. In fact, I find the idea that someone must successfully believe certain propositions to be a form of salvation by works. But in creating a community, one must define what it means to be in the community and not in the community, even if one does not assume that “in the community” is equivalent to salvation.