you cant its impossible
terms like evil are entirely subjective
one man's evil is another man's holy work
. . . that which is in opposition to God's will and purpose. . .
Evil is anything that opposes life or causes suffering
neologist wrote:Defining evil in those terms means you must first define "God", then go on to define what His "will and purpose" is before you finally say evil is the opposite.. . . that which is in opposition to God's will and purpose. . .
That begs the question of the definition of "morality of a culture".