How did Catholic and protestants in N. Ireland do such terrible things to each other?
Catholics and Protestants didn’t hate each other in Northern Ireland for being Catholics or Protestants. They hated each other for being nationalists or loyalists. That is, the vast majority if Catholics in Northern Ireland favored independence from Britain. In colonial America, you would have called them Patriots. The vast majority of Protestants in Northern Ireland were Anglican (Church of England) and favored British rule. In colonial America, they might have been called Tories. The things that were done on both sides were done from that standpoint.
