1. Ecclesiastically, EO is less centralized than Rome yet still has a hierarchy, so there isn't as much of a barrier to entry.
2. Because it is less centralized (and, in the U.S., less prominent that even Jehovah's witnesses; there are ~700,000 EO according to the U.S. census Bureau), it is less apparent to outsiders how the inside truly looks or operates, warts and all. This is all the more true when I hear of EO congregations which experience functional segregation due to the distinctive cultural background of said congregants (read: Galatians 2).
Further, Rome's councils and popes are constantly in the news as going the way of modernism. I don't read much news, but from what I see, EO isn't as exposed. Former insiders to EO (e.g. Joshua Schooping; see his free ebook
here) are relatively unknown - at least, unknown prior to conversions to EO - after which some might think it is too late to turn back (let the rationalizations begin).
3. EO apologists and theologians largely stake their position on appeals to ecumenical councils - or theologians whose theology is said to ground statements by ecumenical councils (Cyril, Maximus, John of Damascus, and Palamas being most prominent, if I am not mistaken).
Examples of fallacies to watch out for in their apologetic: because they are called
ecumenical councils, they must be
biblical councils! Equally fallacious: because
some ecumenical councils are biblically grounded, one must accept that
all others are too.
On the point of tradition, church history, etc., one final point: just like anyone else, people who claim to be Reformed can fall suspect to attempts to rationalize prior ignorance, e.g. "church history is not in monolithic support of Reformed theology; I must have been ignorant/tricked - there must be a true monolith that is different from my prior (Protestant) conception." This is a non sequitur, but more importantly, the reason the fallacy occurs in the first place is because people have a false,
a priori impression of how church history is supposed to look (monolithic). This assumption is the
root of the problem; the
symptom is to elevate historical theology above exegetical theology.
4. I have noticed recently that EO apologists are willing to copy, for example, Reformed presuppositionalism. Thus, they will appeal to the "have your cake (apologetic) and eat it too (monolithic church history)" audience.
5. Reformed theologians have - by and large - polemically ignored Eastern Orthodox theologians. Sure, there may be an article here or single chapter there that in a journal or book that gets lost in the mix of what the focus of the publication
really is, but rarely have I seen a prominent Reformed theologian or pastor debate or engage in a book-length treatment of EO. Compare this to the many popular polemical works against Roman Catholicism.
Obviously, there is a history that somewhat dictates a larger interest in justifying our separation from Rome. On the other hand, in the next century, I could easily see it turn out that EO poses a bigger poaching threat to Reformed churches than Rome. In that respect, it would be better for our apologetics to look to future threats instead of looking back at old ones.
Then again, this is admittedly tricky. What you don't want to have happen is something like what happens in the 1880s-1890s with higher criticism, where
The Princeton Review gave a platform to heretics to debate their false doctrines and thereby legitimate/popularize them. Of course, this is somewhat reductionistic - there were other reasons for the increase in popularity of higher criticism, e.g. that seminaries were sending candidates oversees to Germany for training in the first place - but I don't see any reason to invite a heretic to a debate on my home turf. The best that could be hoped for is that people become more confident or assured that Reformed theology can handle heretics (it can, but a verbal debate isn't the only mode of communication to show that, let alone the best mode).
Along these lines, it was wise of Bahnsen to debate Stein - in a secular university, when he was in the minority, and was able to ably defend his position. In that context, it's really only Bahnsen who could hope for the popularization of his view. So would it be wise of a Reformed theologian to debate an EO? It depends on the context.
Perhaps publications (or, less plausibly, conferences) are safer in terms of established ways of getting information out. In any case, resources on EO by Reformed Christians are scarcer to the layman than resources on most other heresies (even ones smaller in number). Again, this reduces the barrier to entry.
6. Finally, I think there are legitimate questions of Reformed worship that deserve legitimate answers. For example, the question of artistry in the church. Is it wrong to desire a beautified church? I don't think so. Was it wrong that the temple was beautified? Is there a typological case for a beautified church (consider: was Eden itself meant to be beautified)? Why not?
I'm not talking about venerating icons, whether images of Christ can be created, etc. I'm talking about whether the physical construction and layout of a church can be deliberately made attractive. I think this is a legitimate question, even if it is not a legitimate desire (I haven't heard a good reason why it is an illegitimate desire myself).
If a congregant has this question, how often is it that his pastor (who, let's say, thinks it is an illegitimate desire) is giving a good answer to this question? Is it a good answer to simply appeal to what Puritans thought without also expressing their reasons (let alone whether those reasons are biblical)? Is it a good answer to say that the purpose of a "simple" (read: unattractive) church layout is to avoid distractions? This sounds like if I were to tell my students I can't decorate my classroom because they would be too immature to handle it when I'm lecturing.
Just like EO apologists are becoming more aware of and willing to copy presuppositional arguments, they are also becoming more aware of Protestant resources on biblical theology - including but not limited to the rampant speculations of federal visionists - and pivoting the same arguments to the need for a "higher liturgy." Yes, we must avoid the errors of federal visionism, but we must also understand the motivations for the questions they raised before we throw out
everything they say. That includes understanding the need for a developed hermeneutic of typology that avoids the extreme of Marsh's dictum on the one hand and runaway typology on the other. Does such exist? You tell me.
I could well be ignorant on this last point: perhaps many Reformed Christians may give good answers to these sorts of questions. Then again, that is sort of the point: if I'm ignorant, I can understand why others might be as well. Further, the principle of this point is that regarding some questions, I think we would do well to respond with a measure of pause and grace. If this so happens to be a question that has an obvious answer, there are still other questions and questioners which and who don't deserve a slam-dunk response. Most people don't like getting dunked on, even with the truth.
7. A final point that dovetails with what I just said: it's okay not to have all the answers at the time these questions are raised. Answers to questions often are discovered over time. Scripture is materially and formally sufficient to defend the doctrine of the Trinity,
sola fide, etc., but until such heresies arise that require sharper focus in how we answer them, it is often the case that questions that go unasked also go unanswered.
These considerations are not all equally easy to see or deal with. Until people are settled enough in their assurance of Reformed theology to believe that - and to tactfully, humbly, and truthfully project that confidence in the presence of others who are not - it is objectively unsurprising (if personally unsettling) that the whiff of a new wind of a new doctrine or question might carry some away from the faith.
