From Satan Service
As conceived by dualist religious, 'evil' is a category of disobedient behaviour or the results therefrom related to the direction and moral code of their cosmic deity. Typically this code does not apply to the supposed activities of the god itself, but is instrumental in guiding the condition of superordinary beings such as angels (who can 'fall from grace'), or human beings (who can 'forfeit Salvation' -- afterlife residence with the cosmic god in a heavenly abode).
The particular details of what constitutes 'evil' varies by culture and cult, though there are some commonalities established amongst these based on the fact that humans are similar enough as a species to prefer certain social standards of ownership, desires for autonomy and pleasure, and the avoidance of containment and torment.
By many cultures evil has been personified, and this has led those reacting to the abuse of subversion ideologies to composite and champion such personifications in revised form as heroic figures, incorporated within religious constructions known as 'Satanism'.