In the Shikaku-Mon TL from Gurps AE, Francis Xavier has a Portuguese companion, survives his fever, lives on for 20 more years -> Japanese jesuits, more converts, and some Christian saving Oda Nobunaga from being murdered (although that's a legend). At the end, the Christians are too numerous to be eradicated as IOTL. From then on, it's only a matter of time.
Your challenge is to have Japan as a mostly catholic country by 1899, with a POD no later than the arrival of the first portuguese at the XVI Century.
In 1613 (OTL 1616), Tokugawa Ieyasu dies of a fever. Several clans rally around Toyotomi Hideyori, heir of Toyotomi Hideyoshi, as the rightful Shogun.
When Tokugawa Hidetada demanded assistance from Date Masamune, they quarreled.
With the wannabe Shoguns battling in the south, Masamune consolidates his position in the north. In 1620, Luis Sotelo and Hasekura Tsunenaga return from their trip to Mexico and Europe. From their trip, trading relations are established with Spain and a new diocese is formed.
By the 1630s, there is a Portugese/Jesuit diocese in Nagasaki, an English trading post in Edo, and a Spanish/Fransican diocese at Sendai. Will Toyotomi Hideyori prevail? Or will Tokugawa Hidetada retain his position as Shogun? Or maybe Date Masamune will unite Japan under the Date Shogunate?
By this time there is no central authority that can abolish Christianity. Chances are that the Europeans will influence the outcome in some way.
http://en.wikipedia.org/wiki/Date_Masamune
http://en.wikipedia.org/wiki/Luis_Sotelo
http://en.wikipedia.org/wiki/Japanese_warship_San_Juan_Bautista
http://en.wikipedia.org/wiki/Hasekura_Tsunenaga
especially the section Aftermath
http://en.wikipedia.org/wiki/Battle_of_Sekigahara
especially the section Establishment of an English trading factory
http://en.wikipedia.org/wiki/William_Adams_%28sailor%29
This has some of its own possibilities.
[URL="http://en.wikipedia.org/wiki/Arima_Harunobu"]http://en.wikipedia.org/wiki/Arima_Harunobu[/URL]
I really like that idea. So much that I'm thinking about doing a Timeline about it, especially around Date Masamune.
Not sure. Something like Germany or the USA in the sense that there's no predominant religion: 45% Catholic, 15% protestant, the rest buddhist.
I don't mean Catholic in the sense of the Shogun being a puppet of the pope. Catholic in the sense of just being christian.
A Catholic Japan, as opposed to a Japan with a large Catholic population, seems fairly unlikely to me.
Given the fate of Catholics OTL, I mean.
And the Jesuit habit of treating Christians as vassals of the king of Spain.
Perhaps if the Jesuits cut that out, people in high places stop fearing Catholicism as a subversive influence?
A Catholic Japan, as opposed to a Japan with a large Catholic population, seems fairly unlikely to me.
Given the fate of Catholics OTL, I mean.
And the Jesuit habit of treating Christians as vassals of the king of Spain.
Perhaps, but one is tempted to say that then they wouldn't have been the Jesuits.
Is flacking for the King of Spain an intrinsic part of being a Jesuit in the same way that being Catholic and intellectual are?
It is when the only way to get to Japan is via Spanish (and Portuguese, who have a Spanish king...) ships.