Catholicism
In 1054, an Eastern part of the Catholic Church severed itself, in the East-West Schism. The church in Western Europe which followed the Pope, became known as the Roman Catholic Church. The churches in the rest of the world, which did not think that the Pope should lead all Christians, became known as the Orthodox Church. "Orthodox" means "correct belief;" as they believe that they have kept the teachings of the early church, and the Roman Catholics have not.