Ok, Imma rant on this again...
It literally brought about the Great Schism, caused more division between the Jews, Christians, and Muslims, which divided the Ottoman Empire even more, and more events, nationalism, imperialism, militarism, alliances, the stuff still happening because of the fourth crusade causing the assassination and boom, WWI. Then after the war the events that happened leading up to Hitler. The division because of the fourth crusade also fed more of the Christian anti-Judaism, which was one of the things that contributed to the Nazi Aryan Racial Theory