A god is a supernatural being that is thought to be extremely powerful and worshiped as part of a religious belief system.
On Bajor, the Prophets are worshiped as gods by the bulk of the populace. A smaller group worship the Pah-wraiths, the exiled enemies of the Prophets, as the true gods of Bajor. Others, especially some of those Bajorans born off-world during the Cardassian Occupation of Bajor, prefer only a secular, non-religious interpretation of the Prophets. (DS9: "Emissary", "Covenant", DS9 novels: Avatar, Milennium)
There have been numerous religious beliefs in Human history that have worshiped either numerous gods (polytheism) or one single all-powerful God (monotheism).
The Hydran religion worshiped a large variety of gods. (TOS video games: Starfleet Command (game), Starfleet Command Volume II: Empires at War, RIS Bouteina, Star Trek: The Stoneship Files: "Cruchitude Dump")