History Memes

So just to correct the record here, the spread of Buddhism was done through severe wars and good old religious rewriting and recontextualizing of historical events and local mythology. It took a few tries and several centuries of propaganda before that settled down. Hell, the only reason Japan became a big Buddhism spot the first time around is the few huge temples that were built quickly by Chinese money (edit for correction: Korean initially) and preachers lobbying the rich and the powerful, because a couple big families near the throne decided that it could make them money. So it didn't really do Japan good until it was completely integrated and everything was rewritten, actually. And the rewriting that worked was "pretend that actually Shinto and Buddhism are really the same thing" (honji suijaku). Which shouldn't be too foreign if you know anything about Christian conversion of countries. ... Or ancient Greek conversion of countries, or anything else, for that matter.

On the other hand, Japan is currently known on that regard for integrating anything they see and having multiple faiths coexist, so it shouldn't really be that surprising that anything would be allowed to mix in. Though I don't know exactly how accepting the people were at the time beside how the ruling class was divided between converts and antagonists - just like when Buddhism came in.

So it's a bit both not really surprising that Christianity was accepted by the people, and also not the first time a foreign religion tried to wipe out the local religion of Japan through the people in power. No matter which way works, it's not a surprise because none of it is the first time, you just roll the dice to see which one makes it through this time.

What's different is that Christianity tends to be the one that doesn't want to coexist. I mean, Buddhism tried that too, but it ended up as part of the mix. So, the usual MO for Christianity is to target a few rich families in high positions and in trouble to get funds, kickstart some buildings, create an illusion of importance, and make that the new normal. Which is pretty much how it went for Buddhism. But here, the Edo shogunate shut down those big convert families (and of course a big war happened around them), so there was no big religious center or two to gather more money and start the cycle, so the converts stayed hidden instead, which diminished the "return on investment" and killed the adoption rate.

Preying on suffering people who already have nothing to lose is a secondary step to all that - though there was no shortage of oppressed people in Japan for a very long time. Spreading a grassroot-like movement would be more in line with what should work, it's just that it would take centuries of the government just slaughtering the sect of weirdos, until someone in power converts the whole country in the name of all the martyrs (that should also sound familiar). But that's not what Christianity has been doing in that period where it just figured it could walk in and do whatever they wanted. It's just not the oppressed people getting swayed in that can change that on the scale of a country. So, shutting down the funding from the rich families is what did it in.

Also, conquest was another drive of the spread of Buddhism, like around the 8th and 9th centuries when they were still wiping out the north, powerful families were still the ones using that opportunity to build more big temples, both in the capital and in the newly conquered territories, and spread more propaganda. That conquest process was killed when the country actually got unified just when the Christians tried to come in.