Final answer:
Defining religion is challenging due to the existence of sacred and secular rituals, unclear distinctions between natural and supernatural, and varying rituals across cultures. The assertion that 'only one religion can be true' is not a scholarly problem but a subjective belief, and similarities between religious and secular practices add further complexity.
Step-by-step explanation:
The task of defining religion is complex because it encompasses a variety of beliefs, practices, and cultural norms. One major issue with defining religion is recognizing both sacred and secular rituals and their overlap in certain cultures. Additionally, the blurry line between natural and supernatural elements within different societies complicates the clear identification of a belief system as a religion. Varied behaviors for religious occasions and the existence of multiple religions also pose challenges. However, option 'd' within the original question—'only one religion can be considered true, so all others must be classified as myth'—is not a valid problem with defining religion, as it incorporates a subjective claim rather than an objective difficulty in categorization.
Another aspect that makes defining religion difficult is its similarity to other belief systems with ritual-like behavior in secular contexts, which can confuse the distinction between religious and non-religious practices. Anthropologists and sociologists like Émile Durkheim and Sir James Frazer have offered various definitions and perspectives that reflect the diversity and complexity of religious phenomena across different cultures.
Answer: d. only one religion can be considered true, so all others must be classified as myth