The problem is, people think the name of a religion means the organised form of that religion (E.G: Catholicism = pope). In reality, concepts of Christianity, Paganism and other common beliefs were the backbone of violence in the middle ages. People fought and respected a king who claimed divine connection to God or Eire or Thor etc. It was also the way the kings (minority) could take advantage of the peasantry (majority). They feared revenge by god, the Gods.
From what I read, Christianity was loose during the early middle ages, instead of one centralized church. It wasn't until the 11th century that a centralized church actually took hold of the West. Until then, there were wars between countries that had enourmous differences. Etc.
So that's why. What do you guys think?