Some people are especially fond of saying that everything happens for a reason. It may be true in the sense that almost nothing is totally random. I don't really think that is what is meant by most of the people who say it, though. The implication is, instead, that every occurrence on this Earth is somehow divinely inspired or foreordained. It may make the people who say it feel good in a touchy-feely sort of way, as in God is in control of us all, you know. He's got the whole world in His hands. (Pardon me for a moment while I become ill.)
If one really stops to ponder the world in a deeper, sense, on the other hand, such a philosophy shouldn't be comforting. I, for one, can accept acts of violence or the general bad things that some people do to others with less anguish if I think it's the work of an individual or small group of people motivated by selfishness, greed, or other evil ideas than if I think it's all part of God's plan and that God actually intended for the horrible thing to happen. Why would God want Charles Manson to mastermind murders? Why would he give assent to the killing of a very pregnant Laci Peterson? Why would God be a party to a theater shooting? How could God go along with three preschool teachers organizing, facilitating, and filming a bloody fight between two three-year-olds? What about child molestations? I don't buy God's participation in any of it.
Evil is in the world, whether it's legitimately inspired by Satan or merely exists in the hearts, minds, and actions of people. I personally don't buy the argument of Satan's responsibility for evil much more than I think every evil deed is part of God's plan, but that's just my spin. Even if Satan were alive and thriving, I'm not sure why he'd need to do anything in the name of iniquity. There are enough people in the world willing to commit heinous acts that Satan could just as easily sit by his fire toasting marshmallows and watching it all unfold.