Theism, polytheism, and atheism as categorization
Monotheism claims one god exists; polytheism claims many; atheism claims none; deism claims a creator exists but doesn't intervene. These are mutually exclusive metaphysical positions about the number and nature of divine beings. They differ fundamentally from how religions organize ethics, cosmology, or afterlife beliefs. A religion might be monotheistic but disagree with another monotheistic religion on nearly everything else.
Agnosticism, often confused with atheism, actually answers a different question: whether we can know whether god exists. An agnostic atheist claims god probably doesn't exist but cannot be certain; an agnostic theist believes but acknowledges uncertainty. These positions cut across the theism spectrum and reflect epistemology rather than metaphysics.
Afterlife, ethics, and cosmology across traditions
Religions vary widely on what happens after death: eternal judgment (Christianity, Islam), reincarnation (Hinduism, Buddhism), no persistence at all (some forms of atheism). Ethics differ too: some traditions locate morality in divine commands, others in natural law, others in enlightenment or flourishing. Cosmology ranges from creator-based beginnings to eternal universes.
No single axis captures all variation. Buddhism offers sophisticated cosmology and ethics with no god-figure; Christianity emphasizes divine relationship and judgment; Confucianism focuses on social harmony through ritual. Comparing traditions requires recognizing which dimensions you're examining, since a tradition strong in one area might make minimal claims in another.