Many have incorporated a god of death into their mythology or religion. As death, along with birth, is among the major parts of human life, these deities may often be one of the most important deities of a religion. In some religions in which a single powerful deity is the object of worship, the death deity is an antagonist against whom the primary deity struggles. The related term death worship has most often been used as a derogatory term to accuse certain groups of morally abhorrent practices which set no value on human life. In monotheistic religions, death is commonly personified by an angel or demon instead of a deity.