Hey, I'm vaguely back. Unrelated to the current conversation (sorry), but, with the resettling of Christian Iberians in Ireland, and the lack of conquest of Ireland, there are some key things I'd not considered before;
- Numerous Christian thinkers came from Iberia. Key among them in my mind here are Ss. Ignatius of Loyola and Francis Xavier, founders of the Society of Jesus (the Jesuit Order).
- Ireland was, at one time, a key center of western Christianity, and was singularly more resilient to conversion than most nations within the Renaissance; Catholicism was not a 'choice', it was a part of Irish culture, and Protestants and Reformists were shunned, beaten, and often killed when they could (in the remnants of Irish tribes that managed to avoid interference from the English lords, it was even legal to kill non-'Christians' {the Irish considered Catholics and Orthodox equally Christian for a very long time, and only officially joined the Roman Catholic Church due to concessions during the First Crusade}).
The key thing in these two is that the Irish church (itself a fairly monastic-run body) was extremely interested in converting (or re-converting) people to Christianity. During the Dark Ages, it was the Gaelic-run local churches in Britain that converted the Saxons and re-converted many Britons. Rory O'Connor (the last powerful Irish high king, defeated by the Normans, though Edward Bruce was technically a 'Gaelic' high king {he was of half-Gaelic/quarter-Norman/quarter-Saxon descent}, but I digress) had even introduced the idea of sending missions into the east, and had secured promises of aide from both Catholic and Orthodox powers. The goal was to send missionaries as far as India, to try and convert the Nestorian Christians, and then into China. However, the financing fell through, and it never happened (a revival of the mission almost occured, but the Norman invasion came, and Rory no longer had that authority).
The Jesuits, coincidentally, made major missions into Asia; Francis Xavier converted people in India, China, and Japan, amid other places. Given a similar order's creation in Eire (considering that the high kingship relates to good relations with the church; a noble deemed a heretic or heathen was forbidden to hold any office), and Eire's freedom from any such Norman troubles, revived movements to go east and convert people might be brought up. I was thinking about it due to the conversion events in Japan. The order would probably be something more like the 'Maeli Iosu' ('Followers of Jesus'), by the by, if originating in Ireland.
On a related note; there was almost a 'joint' crusade between pagan/Buddhist/Nestorian Mongols and Christian Europe. Has anyone approached this idea? When the final citadels of Outremer were about to fall, Arghun, the Mongol who ruled Persia, and a vassal of Kublai Khan, sent a diplomat to Europe in 1287. In 1258, Hulagu Khan, brother of Kublai Khan, had defeated the Abbasid caliphate. Then, in 1260, it was a Christian Mongol, Kitbuka, that captured Damascus and Allepo. Arghun, a Buddhist, wanted to encourage the Christian kings of Europe to make a common cause to take the Holy Land from Muslims and drive them into Arabia, if not utterly drive them out of the peninsula and into Africa. He was very fond of both Christians and Jews, but Muslims had always been an agitation to him, and he even used it as an excuse to attack Ahmed of Persia (Ahmed was a Muslim who converted from Nestorian Christianity, though the genuine reason was not due to conversion, but fear of Ahmed joining with the Mamluks).
Arghun wrote to Pope Honorius IV in 1285, suggesting an alliance; the letter was not returned though (Honorius died before he could read it, and successor was not selected yet), so he sent Rabban Sauma, a Christian from Asia, to speak with the Pope (not realizing there wasn't one at the time) and Christian kings. He did eventually meet with Pope Nicholas IV, as well as the king of France, England, Emperor Andronicus, and many others, and all of them seemed to love the idea, and were extremely enthusiastic, but none could set a date for when to begin. Discussion continued for some time, but Arghun was dead before a date could be selected, and the plan fell apart, as Outremer had fallen, so niether side saw much use in continuing negotiation.
Has anyone considered to work with that? The Pope was aware of the Buddhist and Christian Mongols and other Christians in Asia. With Jerusalem still present, a revival of the movement to ally Buddhists, Nestorians, Orthodox, and Catholics to take the Holy Land (the Buddhists weren't overly interested in that matter; more simply that they desired to remove Muslims from about anywhere they came across, if they could, and an alliance with Christians {and even a few Jews, actually} was seen as a prime chance to fight Muslims) might be plausible (perhaps tied with aforementioned suggestion for a 'Society of Jesus' type series of events with missions into Asia). It could provide an interesting, very late 'Crusade' type event.