monotheism

noun

1. the doctrine or belief that there is only one God.

noun

1. the belief or doctrine that there is only one God

n.“belief that there is but one god,” 1650s, from Greek mono-, comb. form of monos “single, alone” (see mono-) + theos “a god” (see Thea). A belief in one god. Judaism, Christianity, and Islam are all monotheistic religions. (Compare polytheism.)