An enemy in the Bible refers to people who are in the love of evil and the false thinking that springs from evil. On a deeper level it refers to the forces of hell itself, and on an abstract level it refers to evil itself and falsity itself – which are, obviously, the ultimate enemies we have to fight.

(Reference: Apocalypse Explained 671; Arcana Coelestia 2851 [1-15], 8282, 8289, 9255 [1-2], 9313)