Hmm, do we have cases where the boundaries of the Roman Empire don't match up well with linguistic boundaries? Probably not, simply because anywhere conquered by the Romans would probably have tended to learn to speak Latin, producing an artificial lowering of language barriers within the empire.

Hmmm. I don't know enough history to be able to name specific situations, but what about the other way round - countries that learned Latin without being conquered? (Perhaps for ease of trading?)

Though in the most famous recent case I can think of -- the Soviet Union -- it seems that they weren't very effective in suppressing Christianity

I believe the Roman Empire once tried to suppress it as well. It doesn't appear to have worked then, either.

Going back to the higher-level question of how necessary conquest is to the spread of Christianity: there are apparently something like 100M Christians in China, and not because China was ever conquered by Christians. On the other hand, in the past there seem to have been multiple instances where Christian missions produced a fair number of converts but then the religion largely died out until the next wave of missionaries came in.

Yes; there seem to have been specific instances where missionary conversion worked, and specific instances where it did not.

My impression after all this is as follows. (1) It is certainly not impossible for Christianity to spread without conquest, and there are a few major instances where it has done so. (2) Most of the world's Christians, however, are part of Christian communities that got way way by conquest. (3) Attempts to spread Christianity by mere persuasion are sometimes very effective but often very ineffective.

Those conclusions do not seem unreasonable to me.

I would expect that all these things apply equally to any other major religion.

I think it also depends somewhat on the structure of the religion in question. Judaism doesn't have missionaries, for example, and I don't think there's any way for a non-Jew to become a Jew (I may be wrong on that point, but if there is, the Jews certainly don't advertise it).

Hmmmm. Depends how ingrained the memes are in the material. Oh, you'd certainly have awareness of the memes - but accepting them is a different story, and a certain skepticism in a student (or in a professor) can probably blunt that effect quite a bit.

Even if the memes are that thoroughly integrated, though, the only effect is to make the establishment of a parallel infrastructure that much more appropriate a solution.

I think missionaries are usually sent to particular places by organizations, and when one leaves another goes.

It's not going to be perfect. Sometimes there will be more missionaries than established places to send them, and new missions can be opened - but sometimes a missionary will, through mischance or malice, die before he's expected to do so and there will be no replacement ready to send.

I don't actually know about specific incidences, but there should be enough data on what happens when a mission is abandoned to be able to tell how successful it can be.

You're welcome to be (having had the facts pointed out to you) as surprised or unsurprised as you please; I remark that much the simplest explanation would seem to be that Christianity mostly spreads by military conquest.

That is a simple explanation, yes. Another simple explanation is that Christianity mostly spreads where language barriers don't get in the way.

I don't see either of these two explanations as being significantly simpler than the other.

... Oh, I thought of another way for Christianity to get into a new area that's consistent with the "converting people is really ineffective" narrative. Again, no one claims that converting people is 100% ineffective. So, what you do is to find a place whose rulers are very much in control of the population, and send your missionaries to the royal court or whatever. They probably won't convince the ruler, but if they do then bingo, you've got thousands or millions of new converts fairly immediately. I think this has happened once or twice. I bet it's been attempted a lot more.

Hmmmm. That would be a sensible scenario. There have also been cases where non-Christian rulers, perhaps fearing the political power of the church, made practice of the religion illegal, with severe punishments for doing so. Taking the two together, it seems fairly clear that converting the ruler would be a very important step for many successful missionaries.

Huh.

Okay. In this particular real-life example, though, it is clear that the politicisation is in the infrastructure around the science, not in the science itself. That is to say, learning climate science is not memetically dangerous - it is simply difficult to get a paper published that does not agree with certain politics. And that is bad, but it is not the worst possibility - it means that someone merely studying climate science is safe in so doing.

So, in this particular case, the solution of studying climate science oneself, becoming an expert, and then forming a suitable opinion is a viable strategy (albeit one that takes some significant time).

(An alternative solution - which will also be a hard thing to do - is to create some form of parallel infrastructure for climate science; another magazine in which to publish, another source of funding, and so on. There will likely be serious attempts to politicise this infrastructure as well, of course, and fending off such attempts will doubtless take some effort).

But "amateurs should defer to experts", in reference to Christianity, doesn't mean "amateurs should accept the experts' word about Christianity," it means "amateurs should accept the claims presented by Christianity". There's nothing comparable for Shakespeare. In this sense, neither experts nor schools teach Shakespeare at all.

Um.

Going back to the comment that started this all - over here - shows that the quote originally comes from this page, which is an essay written from the atheist perspective on how to go about arguing the historicity of Jesus. The 'experts' in question appear (to me) to be not theologists but historians, seeking whether or not a given person, referenced in certain historical documents, actually lived at one point or not, and the author bluntly states that he expects the odds of said existence, using his best estimate of requisite probabilities, to be about one in twelve thousand. (He then goes on to say that this is far from the least likely claim in the Christian faith; supernatural miracles are far more unlikely, and thus far better things to call into question).

So, no, the original context does not say that amateurs should accept the claims made by Christianity (and it does not define professionals by their religious leanings). It says that amateurs should not take a firm position on a question where the experts do not take that firm position. (It does not say that the amateurs have to agree with the experts when those experts do take a firm position, amateurs are allowed to remain uncertain).

Schools still teach Latin?

...mine didn't. (It did teach Shakespeare, though).

If all experts are infected with meme plagues, and are able to prevent alternative views from being presented, then you have a problem. This implies that one of the following is true:

• Studying the subject at all carries a strong risk of meme plague infection
• Only those pre-infected with the meme plague have the interest and/or the ability to study the subject
• You're wrong about something - either the presence of the meme plague or its spread or... something.

You could attempt to study the subject to expert level yourself, taking appropriate anti-meme-plague precautions; but you have to be very careful that you're not shutting your ears to something that's really true (you don't want to become a climate-change-denying weather expert, after all) so you'll need to seriously consider all necessary data (maybe re-run some vital experiments). This would take significant time and effort.

I don't know what other strategy could reasonably be followed...

I don't think you need a careful effort to track their exact effectiveness. It would be fairly obvious in a couple of generations that peaceful missionaries would fall in one of two categories - either they have some success (as evidenced by some number of converts that they win over) or they have no success (as evidenced by every missionary outreach pretty much collapsing as soon as the missionary either leaves or dies).

A careful effort to track effectiveness could tell the difference between slight success and strong success, but I think that even with a merely cursory checkup people could tell the difference between some success and no success at all.

If you look at the places where there are a lot of Christians, they do seem to match up pretty well with (1) where the Roman Empire was plus (2) places colonized by countries that used to be part of the Roman Empire.

I'm not surprised. There are many possible explanations for this; a sufficient explanation might be that these are places that early (Latin-speaking) missionaries could be reasonably sure of finding Latin-speaking people, and thus were not required to face the additional hurdle of learning a new language first.

One obvious counterexample is Korea, which (I think) is evidence that missionaries can sometimes introduce Christianity to a new place with long-term success. But what others are there?

Hmmm... would Japan count?

(Incidentally, I think your analysis is incomplete. Another way to introduce Christianity to a new area would be immigration. I don't know to what extent this has actually happened.)

That is true. I don't know to what extent that has happened either, but I imagine it would be accompanied (if successful) by a very strong spread of the immigrant's culture in other ways, as well. (Such as language).

A brief Google points me at this fellow. He was a medieval Fransiscan missionary to China, and established what appears to have been a reasonably successful church there that stayed around for about forty years after his death (until the Ming Dynasty arose in 1369 and expelled them from the country).

I'm pretty sure that the main modern transmission vector for Newtonian physics is schoolteacher-to-child (which is very similar to parent-to-child, except that the parent hires an intermediary). Mind you, I don't have any stats or data handy to back that up, it's just a general impression.