Now for evil. I think we have to distinguish between banal evil and true villainy.
The Banality of Evil was a phrase coined for a report on how the Nazis could attempt to exterminate any number of groups without being a group composed entirely of monsters. As Terry Pratchett put it, "There are hardly any excesses of the most crazed psychopath that cannot easily be duplicated by a normal kindly family man who just comes in to work every day and has a job to do."
This sort of evil comes from the third pillar of morality. People on the outside don't count. You don't betray family or friends, you don't steal from them, or kill them. People on the outside just. Don't. Count. Granted, you have to go out of your way to dehumanize them and demonize them before you're willing to do really horrible things to them (a dozen or so centuries of hearing "perfidious Jew" as part of the Catholic liturgy every year probably helped the Nazis demonize their victims; perfidious originally meant unbelieving but somehow, impossibly, it came to mean "treacherous").
The other sort of evil is that sensationalized by Jack the Ripper and Hannibal Lecter. In somewhere near 5% of the population at large are people with no empathy and no remorse. The terms are confused between psychopath, sociopath, and antisocial personality disorder. Generally, these people have poor impulse control and no empathy for others. Whereas the moral impulse in the majority of people is governed by two parts of the brain, one utilitarian (sure, kill one guy and distribute his organs to save five) and one empathetic (kill a person to save five? You monster!), the psychopath lacks the empathetic response. They don't always become serial killers and monsters, but the majority of violent offenders in prison show signs of sociopathy.
Whence the sociopath? Whereas morality is a system whereby evolution has gamed for cooperation for mutual benefit, sociopathy is a system that parasitically takes advantage of the first. Too many sociopaths and society couldn't possibly exist. Too many backstabbing bastards and there would be no potential benefit to backstabbing. Only if sociopaths are a minority can they succeed. When 95 times out of 100 you can trust your buddy to do right by you, the backstabbing bastard can really make a killing.
This isn't an unsuccessful strategy, no matter that we like to believe people get their comeuppance. A bastard-coated bastard with a creamy bastard filling can really get ahead, particularly in a more populace society where strangers are common. A questionnaire filled out by CEOs with questions hidden within to indicate sociopathy indicated it's more common (perhaps twice as much as in the general population). It's not hard to imagine that being a ruthless jerk could make you successful on Wall Street, legally or not (see: Enron).
In the end, whether dealing with the banal evil or dispassionate sociopathy, evolution easily explains evil. As the existence of the theodicy problem demonstrates, the god hypothesis really doesn't.