Have to disagree with this part. Hus expressed similar ideas a century earlier, but they didn't catch on because it was the wrong moment. Luther expressed what a lot of people were thinking at the moment, not just fellow separatists like Zwingli but also those who remained loyal to the Catholic Church like Erasmus and Pole (the Counter-Reformation was inspired by the same sources as the Reformation--ad fontes predates Luther by nearly a century). One scholar called the Reformation a debate in the mind of St. Augustine: Protestants endorsing Augustine's soteriology, Catholics his ecclesiology.
I'm not discounting Luther's work or significance, but if you eliminate Luther, you still get the Protestant Reformation...possibly with a more diplomatic, less irascible leader who didn't view all of his fellow reformers as personal nemeses. (The same happened on the other side. Cardinal Pole was sympathetic to the Reformation and might have found a compromise with the Protestants, other than Luther, had he been elected pope.) Also, Luther didn't single-handedly change European history; there were hundreds of other reformers and hundreds of thousands of their followers. Without them, there would have been no Reformation. Again, without Luther, you still get the Protestant Reformation; he was just a fiery, intelligent, belligerent center point for a tide that was already incoming and had already begun to simmer in places like Switzerland, Italy, and the Netherlands. (We don't usually associate Italy with Protestantism because Italian Protestants were largely forced to emigrate or recant, but both Renaissance humanists and the Oratory of Divine Love were important forebears of the Reformation.)
That being said, Luther would be a very fun leader, though his dialogue would break the E10+ age rating. Still, if they put the effort in, his boisterous irascibility and petulance would make for a great presence in the diplomacy screen.
Not just by that. The Protestant Reformation directly led to secularization as the Western Christian world fragmented, leading to the privatization of religion and increasing public focus on commerce in its place. This happened in Catholic as well as Protestant countries as both sides had to accept that religious pluralism was preferable to endless religious warfare like the Thirty Years' War and the St. Bartholomew's Day Massacre (somehow Catherine de Medici returned).