Good and Evil.. connect the dots...
Humans leave trails, it's called evidence. eg, Something as beautiful as music.. at a basic level we can trace it's development, it's evolution. The most complex 80 piece orchestral composition had it's seeds in the simple modal chants of Gregorian monks.
The development of notation and the codification of difficult concepts are all able to be traced back. The romantic, mystical and poetic dimensions to this art are ways we have of understanding how music makes us feel, tools to unwrap the riddle.
Likewise with philosophy and myth.. good and evil evolved as a concept from human experience. Ancient gods were utilitarian, and the ones that seemed to work best, ie. their followers seemed to prosper, attracted a bigger slice of the believer market. In the swill of ideas in the milennia before Christ, Yahweh beat out other popular gods like Baal and Mithras to gain more followers. Around that time the Iranian prophet Zoaroaster distilled the many gods idea down to two, truth and lie, or good and evil, this eventually syncretised into the Xtian version of understanding it of god and the devil.
The trail is there... follow it. There is no special case for Christ, it's just a prism through which to view the world that was built on existing ideas. The supernatural overlay is a poetic and romantic association attached to the idea, just as it is with music, and that is a human constuct as well.