Final answer:
The term 'monotheism' best fits the definition of the belief in one god, distinguishing it from 'polytheism', which involves belief in multiple deities.
Step-by-step explanation:
The word from the list that best fits the definition of 'the belief in one god' is monotheism. Monotheism is a belief system that centers on a single named god or goddess. Some of the largest monotheistic religions in the world today are Christianity, Islam, and Judaism, which together have billions of followers. On the other hand, polytheism refers to a religion based on belief in multiple deities, exemplified by religions like Hinduism, which has a pantheon of deities. Concepts like totemism involve a belief in a divine connection between humans and other natural beings, but it does not fit the definition of monotheism.