The article defines "tribal congregationalism" as a situation in which "particular errors find toleration in specific Presbyteries that remain unaccountable to the denomination as a whole." The author is concerned that the PCA (Presbyterian Church in America) has become encumbered with this very un-presbyterian situation, and he describes why in the article.
In the course of the article, the author describes the basic workings of presbyterianism as these are laid out in the PCA's Book of Church Order:
We see these principles generally at work in the PCA’s Book of Church Order (BCO). We have three levels of church courts, each with specific tasks and functions assigned, specific expectations, and each empowered to carry out their tasks and functions as delineated in the BCO (BCO 1-1; 1-5; 3-2; 10-1; 10-2; 11-4). Through review and control (BCO 11-4; 40), each court is held accountable to the broader courts. That is, sessions are held accountable to Presbyteries through the review of their minutes and general knowledge of their activities. Presbyteries, in turn, are held accountable via the same tools to the General Assembly. That’s Presbyterianism 101.
When that process breaks down, we have processes for church discipline (BCO Chapters 29–40). Individual courts hold their members accountable through investigations, counseling and, as a last resort, trials. Each court’s execution of the discipline process is reviewed by the next broader court for their fidelity to our Constitution – the Westminster Standards together with the BCO. That’s Presbyterianism 102.
He then describes how this basic system has broken down in the PCA, resulting in "tribal congregationalism":
The tribes refer to Presbyteries that tolerate officers holding, practicing and/or teaching specific errors within their boundaries. I witnessed firsthand that seminary graduates know which Presbyteries are likely to accept their paedocommunion views, for example, and in which Presbyteries to avoid even attempting ordination. Federal Visionists have a very good idea of which Presbyteries they shouldn’t bother transferring into (Leithart obviously isn’t as smart as some folks think he is). And so on with intinction, theistic evolution, female deacons, etc. Each erroneous officer or candidate seeks out safety in his applicable tribe. Some tribes overlap or tolerate multiple errors, others do not. Safe conversations seek out supporting tribes.
The congregationalism part of the term comes from the lack of accountability outside the tribe. We nod and wink at specific Presbyteries that tolerate officers who practice or teach Federal Vision, paedocommunion, intinction, female deacons, theistic evolution, et al. A majority of the commissioners at General Assembly have apparently consistently desired to avoid offending or judging deviant officers. Net result = no accountability. Specific errors thrive within the bounds of each tribe without accountability to the denomination at large. That’s what I call tribal congregationalism, and ultimately it will destroy the PCA.
In his conclusion, he writes:
The empowerment and mutual accountability of Presbyterianism is fundamentally incompatible with tribal congregationalism.
I think the author's use of the term "congregationalism" is particularly helpful in describing the problematic situation he wishes to point out in the PCA. Presbyterian church government is based on the concept of the formal unity of the church and formal mutual accountability between church officers and church courts. Officers are subject to other officers on the session, sessions are subject to mutually-binding presbyteries, presbyteries are subject to mutually-binding higher synods, etc. Congregationalism, on the other hand, rejects such formal unity and mutual accountability.
The author's observations apply on a larger scale as well--the world of Reformed denominations. There are many currently-existing Reformed denominations that have no mutual accountability with each other. They often have some differences in doctrine and/or practice, but there is no formal ecclesiastical structure in place to reconcile these differences because they do not consider themselves as united under mutually-binding higher councils. According to presbyterianism, this situation implies that all of these denominations are rejecting each others' de jure legitimacy and authority, for how otherwise could they justify remaining independent from each other? But many Reformed people have come to think of the de jure visible church as nothing more than one big happy family of independent Reformed denominations. If "tribal congregationalism" is an apt phrase to describe a situation within a denomination where different presbyteries hold, in effect, different standards of doctrine and practice without being accountable to each other for correction, surely it is also an apt phrase for exactly the same situation in the larger Reformed world, where different denominations accept each others' de jure legitimacy and authority (or say they do) but maintain differences in doctrine and practice that are not amenable to mutual correction because there is no practice of mutual accountability.
We in the modern Reformed world need to make up our minds: Are we going to be presbyterian, or congregationalist (or semi-congregationalist)? If the former, we need to acknowledge clearly that the various existing denominations are in schism from each other and are rejecting each others' de jure legitimacy and authority, and then we can work harder and more intelligently to see if we can fix this serious problem. If the latter, then we need to stop calling ourselves presbyterians and consciously reject our presbyterian heritage, and then those of us who are really presbyterians can find it easier to avoid being fooled by false advertising.
For more, see here and here, and in general here.