I understand "evil" to be a blessing from God. If everyone only did what is good because they have no other choice, then it isn't truly "good" just preprogrammed actions. Man would be nothing more than automatons always doing "good", which can only be good if the choice to be evil is allowed. To give man free will, there must be a choice- choose to "do good" or to "do evil" in all actions. It is that choice, that freedom to choose, that enables one to choose good or to choose evil. I don't buy into that "demiurge" idea, nor that God created "Satan", "Heaven" and "Hell" (Greek concepts taken up by Hellenized Jews and not original to the Hebrew religion) to tempt and punish people. If anything, I see the freedom to choose evil as a blessing for all men- without the choice to commit evil acts there can be no true good.

Just my take on it and I'm, as likely to be "wrong" as "right".