Übergeek 바둑이: Judaism calls it the two Yetzer's. One is the 'God' morality, the other that drives us to marry, have children.

It is not 'evil' as in the Greek sense, but if the second (referred in Egyptian religion as the lesser God) is not commanded by our own 'God' morality.. that's when what we call evil happens.

It is often that the lesser god (Yetzer ra) is called Satan, or the Devil.. this is just bad understanding and the ability to blame supernatural beings for our own failings. It was good in the old days (as one lady explained)... there wasn't much law. And such so called 'pagan' ideas helped control the population.. then religion got and abused it.
From a pure philosophy point... there is no such thing as good or bad.. there is what is.

As for the master and slave classes, Nietzsche's arguments are a bit flawed and does not fully explain Judaic/Christain/Muslim concepts.

But I'm not getting into that here... take about a dozen pages