Humor will not be tolerated!! -Portia

Just in addition to Yellow's answer: while the idea of a benevolent God might not seem to fit the data, upon taking a closer look it's really quite simple to see how it truly fits. The biggest evidence I can offer is agency. I have a personal testimony of the utter necessity and truth of our free will and the effectiveness thereof. I don't think that testimony is one that any reasonable person would deny. Understanding, as we do, that agency is something upon which our whole existence on this earth was predicated (that decision accompanying some trouble in the pre-existence ), it is possibly the most important concept that the average person shares with the gospel.

I'm circumlocuting-- basically, there is evil because man has free will. We know that good would not truly exist without the potential for evil. It just makes sense, even without our mormon knowledge. In order to bring about the greatest good, a God would have to give us the ability to do evil.

I feel like I just said something really simple in possibly the most overdone way. Eh, that's what I mean though-- it's not an answer besides the real answer like W&S would have us avoid, it's just the simplest way at arriving at the conclusion. It rings true in just about everyone's heart. It both leads and follows our sentience. "We know our will is free, and there's an end on't!" ~Samuel Johnson

Agency! It's so rad!

I have a pretty strong philosophy background, so I'll chime in a bit. Proteus, free will is one of the most common answers to the problem of evil. In addition is the soul-building theodicy, which states, in essence, that when we learn and grow from evil that happens to us, the net result is good, ergo, a benevolent God would desire it.

Both of these answers always struck me as a bit incomplete. I think, what I personally have come to realize (and this is more religious than philisophical, though the two have so much overlap, it can't really be differentiated, well, at least) builds somewhat on Yellow's answer. I think we have an incorrect idea as to what "evil" is, in the sense of an eternal perspective. Let's say, for example, that a young single mother is diagnosed with cancer, and, despite all attempts of modern medicine to cure her, she dies, and her three children are left without a parent. Our initial reaction (at least, assuming a slightly less humble ideology than is common in the LDS church) may be, "why would God, if he is so good, take away this woman in the prime of her life? This was a terrible thing to happen." I would submit, that, although it is terrible, it cannot rightly be described as evil. I think that the only good or evil in this world is the choices that we as humans make; this is, in essence, the reciprocal of Lehi's argument. That is, Lehi said, without good and evil, there can be no choice, we must be compelled in one or the other. I'm suggesting, without choice, there can be no good or evil.

Morality, then, comes from our reactions to the things that happen in the world around us. Let us say that one of those three children, presumably of sufficient age to begin thinking about this sort of thing, reasons "No God could allow such a thing to happen. There must be no God." He then begins to live his life in "riotous living", because, since there is no God, he reasons, there can be no consequence for his actions. This, I would suggest, is a true evil, but since agency exists, God cannot force otherwise, and were He to do so, He would be ensuring that good was not produced, since good action, by this definition, must be voluntary. A second of these three children, on the other hand, says, "God has allowed this to happen, for some purpose I can't understand. All I can do is serve him the best I can, and trust that he will allow good to come of this." By this statement, she has made it true, since the good is in her own choices to live well.

Based on this definition, God is not necessarily all powerful (which we, as members of the LDS church, don't believe anyways) since he has created a law that he himself cannot break. Or at least, were he to do so, he would lose his position within the universe. Anyway, sort of a round about way of saying that agency is the answer, but I hope this gives a little more insight into the LDS perspective. As for the question itself, I think this definition can appeal quite universally, even outside of Christian religious schemas.