The figure of Satan as a rebellious fallen angel who opposes God developed during the intertestamental period, influenced by Persian dualistic ideas.

During the time between the Old and New Testaments, Jewish thought was influenced by Persian religious concepts, particularly the idea of a cosmic struggle between good and evil forces. This period saw Satan’s transformation from a heavenly prosecutor into a malevolent being opposing God. The idea of Satan leading a revolt with other angels and being cast out of heaven became popular, setting the stage for the later Christian depiction of Satan as the Devil, the ultimate enemy of God and humanity.