A god is a supernatural being that is thought to be extremely powerful and worshipped as part of a religious belief system.
On Bajor, the Prophets are worshipped as gods by the bulk of the populous. 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 offworld during the Cardassian Occupation of Bajor, prefer only a secular, non-religious interpretation of the Prophets. 
There have been numerous religious beliefs in Human history that have worshipped either numerous gods (polytheism) or one single all-powerful God (monotheism).