But an ecumenic thread will do nothing to a propagandist because his whole purpose is to drag your faith down, not to explain his.
Neither a caucus or an ecumenic thread will close the deal, if the objective is to refute others. You need a format that is open to hostile views being expressed for that.
Which comes back to the original reason for proposing something for consideration.
The propagandist will rely upon certain well-worn argument patterns. Those can be found on numerous websites and are ruthlessly plagiarized from one to another (perhaps with an occasional word change, but that's it).
A reference for us to be able to quickly refute that line of argument (and once refuted to simply ignore the thread) I think would be beneficial.
That is the reason I would propose a caucus designation: because the purpose is not to argue the proposition with those who believe it but to develop a ready resource for those of us who want to put it out of its misery when it pops its ugly head up, regardless of how many of 25 million pages contain it.
(But apparently we have to give the other chance an opportunity to defend the proposition, even though it has nothing to do with positively asserting their beliefs...it only has to do with dragging down somebody else's beliefs. Oh, well)
Some folks are ill-mannered. Some folks can turn any thread, on any topic, into a sewer. Some folks exercise that ability regularly.
The "academic thread" proposal would only work if those who disrupt it face meaningful consequences. Given the behaviour we have all seen on open threads, the academic thread would require a very heavy-handed moderator. No matter the original topic, we're discussing religion here ... things are interconnected, and even valid discussion in good faith will drift. Deciding what comments are valid drift, and what comments are "goat blood" material will require much more intensive moderation than the simple "don't make it personal" rule.
If the mods are willing to take up that burden, of course, the system could work. But let us have no illusions ... it will be a big burden.