The term that BEST describes Isolde’s religious beliefs is B. fundamentalist.
A fundamentalist is a person who adheres strictly to a set of basic principles or beliefs, often religious in nature, and who is resistant to change or new ideas. In this case, Isolde's belief in a literal reading of the Bible and her preference for worshiping with a Bible in Latin rather than modern English translations suggests a strict adherence to traditional Christian beliefs. Her intolerance of other religions also suggests a resistance to new ideas and a desire to preserve traditional beliefs.
While other terms such as animist, shamanic, or cargo cult might describe certain religious beliefs or practices, they are not appropriate to describe Isolde's beliefs based on the information provided.