@kt_ With any religious or spiritual thinking there is something behind it. It isn't obvious and before I knew better I used to say it was nonsense.
For example this chap talks for a good few minutes about this:
It is about 1h 5 minutes if the link does work on here.
His discussion about the Snake is interesting. Because he is saying we Abstracted an actual Serpent / Snake to something that existed in a person and then actually evil.