>>507516254shia islam started as a political movement with different views on who should succeed Mohammed and become the Caliph of the Muslim theocracy. then they started warping the faith. it became a non-canon lore DLC over the actual faith. the sunni vs shia shit started during the "shia century".
>shia rise into power>"become shia, leave the country or die.">lose Jerusalem to the crusadesThe hatred that lingers today is from stories from those times that are still being told in those days. of course it's not universal. you have present day Iraq where sunnis and shias coexist.
https://en.wikipedia.org/wiki/Shi%27a_Century
https://en.wikipedia.org/wiki/Safavid_conversion_of_Iran_to_Shia_Islam
https://www.youtube.com/watch?v=9usSJfx6McE