Actually bulk of Indonesia was converted with a sword,
when first local Sultanates emerged, they quickly conquered everyone else on the islands. It is common misconception that conversion of Indonesia was peaceful...
I convinced myself to read that long wikipedia page from top to buttom for the sake of argument. Putting aside the numerous emphasizes on insufficient historical data about the spread of Islam in Indonesia, one can easily deduce from that long text that early spread of Islam by means of trade relations was truly peaceful which supports my explanations and after reaching a significant level, political struggles among local rulers and other factors such as colonialism threat made contribution to spread of Islam in the region. Thus, claiming that the Islamic conversion of Indonesia was majorly caused by the sword is not a well-meaning argument to say the least. Actually, that's why I suggested academic sources in the first place to evade a quarrel.
This point is very controversial and scholars seem to be divided. If Malay rulers had converted to Islam in order to find allies against the Portuguese, and later Dutch, then this would explain their conversion very easily. The problem is that the dates don't work. The trading cities and power centres converted in a wave travelling from west to east: north Sumatra in the early 14th century, Malaya in the 15th century, Java in the 16th century AD. The process had started before the Europeans arrived. Although this game is called Europa Universalis, not every part of history started in Europe, as you know!
You misunderstood me or I failed to explain my argument properly. The local rulers had already converted to Islam long before Portuguese threat. For instance, even in mid 16th century, muslims of Aceh Sultanate which consolidated power around Malacca and Sumatra sought support from Suleiman the Lawgiver against the Portuguese threat. As you stated above, a considerable number of people in the region already converted to Islam but when non-muslims in the region faced the ravage brought by portuguese, and later dutch (this may be out of eu4 timeframe) converts to Islam saw a rapid increase at the time.
As you have said, there were Sufi scholars in the region. Why were they there, in an area with few Muslims, far from the scholars of Mecca and Cairo? Some of them had been sent by their order (tariqa) specifically to spread and strengthen their faith, so they were missionaries. The most famous is Abd' al-Ra'uf Singkel of the Shattariyya. They taught the Muslim merchants how to live, which included business, which meant that they had to teach Malay rulers how to do business according to Islamic teaching. While there had been Arab traders for centuries, the Sufi scholars seem to have been a new development in the 14th century, which explains why conversions began to happen at that time.
Based on narrow definition of missionary what you said is correct. Yet my point was that trade relations between muslim Arabs and locals was the major reason for spread of Islam in the region. Conversions started long before the sufi scholars came to that region. Local pagans had known of Islam via muslim traders for a long time and sufi masters' efforts to convey this new religion only hastened the process. For instance, one of the companions of prophet Muhammad (saw), Sa'd İbn Abi Waqqas (595-674) is buried in Guangzhou, China. So, Islam's leading figures were in the far east long before the sufi masters, or missionaries as you say and they acted as role models by their life style so that they warmed people's hearts in favour of muslims which facilitated the work for future muslim traders and scholars. So your assumption about the 14th century conversations of sufis is hardly correct.
Yes, all this is true. But you seem to think that this was not a political process. I think your language could be understood as people watching a Muslim doing deals in a small bazaar, admiring their honesty, and converting. But these were not small businesspeople. Trading across the Indian Ocean needed large amounts of capital; these were the multinational corporations of the 14th and 15th centuries. And that had two effects.
I do believe political struggles and elements of international diplomacy affected the spread of Islam in the region and I stated this above. And yes, trade relations and cultural interactions between muslim Arabs and local folks were truly beyond our comprehension.
Firstly, the Muslim merchants managed these complex businesses arrangements through Islamic commercial law, which was more developed than the existing systems in southeast Asia. When the sources talk about the honesty of Muslim merchants, they mean their advanced legal technology. And unlike today, there were no secular lawyers: the legal experts were those Sufi scholars. The only way to access the legal technology was to become Muslim.
Secondly, the Muslim merchants were closely tied together: they met for worship, intermarried, and increasingly belonged to the same Sufi orders. So they naturally tended to do business as a group. If a Malay ruler converted, then he could join this exclusive group (as a I said before, ruler = trader). And when disputes broke out between Malay cities or amongst royal families, the one closest to the Muslim multinational business group had a big advantage. It was a similar situation to the 20th century '
banana republics', where American fruit companies had the power to choose the rulers, without American colonization or invasions.
Nothing to disagree with here.
I may have been unhelpful in introducing an example from medieval Christian Europe into this conversation, as I guess that it may not be something you have studied much. I don't think you could describe that process of Christianization as colonization. I think Danish, English, Swedish, etc. people would be very surprised to hear they had been colonized from Rome and assimilated many centuries after the end of the western Roman Empire! They were not colonized, but converted, and just as in southeast Asia, the conversion of rulers was a deliberate missionary strategy.
But as I said, I think the new game mechanism is a good one for this topic.
It's true that I have a skin-deep knowledge about formation of christian europe but yes, I have no desire to describe this process as colonization. It was a political and cultural process born out of struggle between christianity and pagans which resulted in victory of christianity. For example, Constantine I saw christianity as a unifying factor among his subjects believing that it would shape a brilliant future for them and decided to convert to christianity. I almost forgot christian missionaries' efforts to spread the faith...
As far as I can find, Dr Lee's books have not been translated into English. They have been written in Korean and (translated into???) Turkish. I found only one article in English, published in Turkey, about Islam in northeast Asia (China and Korea). This was very helpful in drawing my attention to an aspect I had not considered before, so thank you for the recommendation. He shows that the first Chinese converts to Islam were Han women who married Arab merchants. Again, we should not imagine young women falling in love with handsome heroes. I'm sure there were many handsome Muslim merchants

, but these were power couples: Han families exchanging their daughters for better access to powerful Arab men. This happened in southeast Asia too and apparently one scholar (Harrison) has argued that intermarriage was the main way Islam spread.
If you're really interested in these matters, I'll gladly help you. Here, the English version of his book in case you consider buying:
https://www.amazon.com/Advent-Islam-Korea-Historical-Account/dp/9290630671
I have Turkish version of this book and it has very interesting piece of work about conversion of southeastern Asia to Islam. Dr. Lee's doctorate thesis about this subject was also a valuable source but I had a hard time to find it.
I think it is more likely that a few key marriages were very important in persuading some of the rulers to convert; certainly the Sultans of Malacca used princesses to persuade other Malay rulers to convert. Again, this closely parallels northern Europe: Augustine of Canterbury's mission was only possible because the King of Kent had married a Christian princess from Francia, and later Kentish Christian kings often married their daughters to pagan kings in return for the right to send missionaries. In fact, a young scholar (Wain) has just written a thesis arguing the first conversion of a Sultan of Malacca happened when Zheng He gave him a Chinese Muslim wife!

This is revolutionary if it's true, but his article was published in a fake journal, so it seems other scholars aren't convinced!
Conversion of Europe to Christianity may have some similarities with conversion of far southeastern Asia to Islam via powerful muslim sultanates in post-imperial era but early conversions to Islam, which is actually the main subject of our discusion had almost nothing to do with spread of christendom into europe in terms of means of conversion.
And thank you for the articles as well.
They pillaged the balkans for 500 years and yet orthodoxy is alive and well even after all that time, even with child abductions and all sorts of other grotesque stuff. The Ottomans did a terrible job converting the balkans, so much so that the current in-game rate of conversion in the balkans is way too high. If anything, Orthodox should be more resistant to conversion.
Words far from common sense. You should put aside such nationalist sentiment and repugnant tone. Speaking of an empire having one of the strongest state traditions along with British and Russian empires like they were merely pillager barbarians doesn't make your wording any less offensive. You can't just preserve your language, your religion, your culture and traditions after being ruled by some intolerant pillagers who had a liking for assimilation of lesser nations. I always find those serbian or bulgarian nationalists hard to understand. To give a few examples, After his Bosnia campaign in 1463 Mehmet the Conqueror made a speech in bosnian and promised full religious freedom to bosnian fransiscans, majority of bosnian people immediately converted to Islam, appreciating such munificence. His son, Bayezid II welcomed both muslims and jews escaping from inquisition in Spain and sent his fleet for their safe evacuation. After ordering repair of the city walls of al-Quds, Suleiman the Lawgiver had the script "La ilaha illallah Muhammadun Rasulullah" (
There is no god but God. Muhammad is the messenger of God) on al-khalil door of city of Al-Quds changed to "La ilaha illallah Abraham Khalilullah" (
There is no god but God. Abraham is God's friend) to emphasize the respect and coherence among three abrahamic religions and dignify the dhimmi minorities of the city. These and hundreds of others were examples of
Pax Ottomana. And finally, a pillager state wouldn't have spent on infrastructure more than they would collect from taxes in the region as the Ottomans did in Hungary in 1560s. Those who don't believe me should try reading academic studies of hungarian turcologists such as Gabor Agoston, Pál Fodor, Géza Dávid and Lajos Fekete. I hope you won't push further with such delusions of yours. Have a good reading...