- Polytheism: religious faith in the existence of N god(s), where N > 1
- Monotheism: religious faith in the existence of N god(s), where N = 1
- Atheism (or "positive atheism," or "strong atheism"): religious faith in the existence of N god(s), where N = 0
- Agnosticism (or "negative atheism," or "weak atheism"): lack of religious faith