Christianity is among the religions that have the biggest amount of interpretations and custom versions believing in subsets or supersets of it ( just for starters, Catholics, Orthodox, Lutherans, Mormons, and a million others). Due to age, evolving interpretations, efforts of modernization and various sects, "Christianity" can mean different things to different people, and enforcing any version of it is bound to piss off any competing sect, religion and all non-religious people, which will probably be the majority.